proc(5)


NAME

   proc - process information pseudo-filesystem

DESCRIPTION

   The  proc filesystem is a pseudo-filesystem which provides an interface
   to kernel data structures.  It is commonly mounted at /proc.   Most  of
   it is read-only, but some files allow kernel variables to be changed.

   Mount options
   The proc filesystem supports the following mount options:

   hidepid=n (since Linux 3.3)
          This   option   controls  who  can  access  the  information  in
          /proc/[pid]  directories.   The  argument,  n,  is  one  of  the
          following values:

          0   Everybody  may  access all /proc/[pid] directories.  This is
              the traditional behavior, and  the  default  if  this  mount
              option is not specified.

          1   Users  may  not  access  files and subdirectories inside any
              /proc/[pid]  directories  but  their  own  (the  /proc/[pid]
              directories  themselves  remain  visible).   Sensitive files
              such as /proc/[pid]/cmdline and /proc/[pid]/status  are  now
              protected  against other users.  This makes it impossible to
              learn whether any user is running  a  specific  program  (so
              long  as  the program doesn't otherwise reveal itself by its
              behavior).

          2   As for mode 1, but in addition the  /proc/[pid]  directories
              belonging  to other users become invisible.  This means that
              /proc/[pid] entries can no longer be used  to  discover  the
              PIDs  on  the  system.   This  doesn't  hide the fact that a
              process with a specific PID value exists (it can be  learned
              by  other  means,  for  example,  by "kill -0 $PID"), but it
              hides a process's UID and  GID,  which  could  otherwise  be
              learned  by  employing  stat(2)  on a /proc/[pid] directory.
              This greatly complicates an  attacker's  task  of  gathering
              information   about  running  processes  (e.g.,  discovering
              whether some daemon is  running  with  elevated  privileges,
              whether  another  user  is  running  some sensitive program,
              whether other users are running any program at all,  and  so
              on).

   gid=gid (since Linux 3.3)
          Specifies  the  ID  of  a  group whose members are authorized to
          learn process information otherwise prohibited by hidepid (i.e.,
          users  in  this  group  behave  as though /proc was mounted with
          hidepid=0).  This group should be  used  instead  of  approaches
          such as putting nonroot users into the sudoers(5) file.

   Files and directories
   The  following  list  describes many of the files and directories under
   the /proc hierarchy.

   /proc/[pid]
          There is a numerical subdirectory for each running process;  the
          subdirectory is named by the process ID.

          Each  /proc/[pid]  subdirectory  contains  the  pseudo-files and
          directories described below.  These files are normally owned  by
          the  effective  user  and  effective  group  ID  of the process.
          However, as a security measure, the ownership is made  root:root
          if  the  process's  "dumpable" attribute is set to a value other
          than 1.  This attribute may change for the following reasons:

          *  The  attribute  was   explicitly   set   via   the   prctl(2)
             PR_SET_DUMPABLE operation.

          *  The   attribute   was   reset   to  the  value  in  the  file
             /proc/sys/fs/suid_dumpable (described below), for the reasons
             described in prctl(2).

          Resetting the "dumpable" attribute to 1 reverts the ownership of
          the /proc/[pid]/* files to the process's real UID and real GID.

   /proc/[pid]/attr
          The files in this directory provide an API for security modules.
          The  contents  of  this directory are files that can be read and
          written in  order  to  set  security-related  attributes.   This
          directory  was  added  to support SELinux, but the intention was
          that the  API  be  general  enough  to  support  other  security
          modules.   For  the  purpose  of  explanation,  examples  of how
          SELinux uses these files are provided below.

          This directory is present only if the kernel was configured with
          CONFIG_SECURITY.

   /proc/[pid]/attr/current (since Linux 2.6.0)
          The  contents  of  this  file  represent  the  current  security
          attributes of the process.

          In SELinux, this file is used to get the security context  of  a
          process.   Prior to Linux 2.6.11, this file could not be used to
          set the security context (a  write  was  always  denied),  since
          SELinux  limited  process security transitions to execve(2) (see
          the description of /proc/[pid]/attr/exec, below).   Since  Linux
          2.6.11,  SELinux  lifted  this  restriction and began supporting
          "set" operations via  writes  to  this  node  if  authorized  by
          policy,  although  use  of  this  operation is only suitable for
          applications that are trusted to maintain any desired separation
          between  the  old  and  new  security  contexts.  Prior to Linux
          2.6.28, SELinux did not allow threads  within  a  multi-threaded
          process  to set their security context via this node as it would
          yield an  inconsistency  among  the  security  contexts  of  the
          threads  sharing  the  same  memory  space.  Since Linux 2.6.28,
          SELinux lifted  this  restriction  and  began  supporting  "set"
          operations for threads within a multithreaded process if the new
          security context is bounded by the old security  context,  where
          the  bounded  relation  is defined in policy and guarantees that
          the new security context has a subset of the permissions of  the
          old  security  context.   Other  security  modules may choose to
          support "set" operations via writes to this node.

   /proc/[pid]/attr/exec (since Linux 2.6.0)
          This file represents the attributes to  assign  to  the  process
          upon a subsequent execve(2).

          In  SELinux,  this is needed to support role/domain transitions,
          and execve(2) is the preferred point to  make  such  transitions
          because  it offers better control over the initialization of the
          process in the new security label and the inheritance of  state.
          In SELinux, this attribute is reset on execve(2) so that the new
          program reverts to the default behavior for any execve(2)  calls
          that  it  may  make.  In SELinux, a process can set only its own
          /proc/[pid]/attr/exec attribute.

   /proc/[pid]/attr/fscreate (since Linux 2.6.0)
          This file represents the attributes to assign to  files  created
          by  subsequent  calls  to  open(2),  mkdir(2),  symlink(2),  and
          mknod(2)

          SELinux employs this file to support creation of a  file  (using
          the  aforementioned  system  calls)  in  a secure state, so that
          there is no risk of inappropriate access being obtained  between
          the  time  of creation and the time that attributes are set.  In
          SELinux, this attribute is reset on execve(2), so that  the  new
          program  reverts  to  the default behavior for any file creation
          calls it  may  make,  but  the  attribute  will  persist  across
          multiple  file  creation  calls  within  a  program unless it is
          explicitly reset.  In SELinux, a process can set  only  its  own
          /proc/[pid]/attr/fscreate attribute.

   /proc/[pid]/attr/prev (since Linux 2.6.0)
          This  file  contains  the security context of the process before
          the  last  execve(2);   that   is,   the   previous   value   of
          /proc/[pid]/attr/current.

   /proc/[pid]/attr/keycreate (since Linux 2.6.18)
          If  a  process  writes  a  security  context into this file, all
          subsequently created keys (add_key(2)) will be labeled with this
          context.   For  further  information, see the kernel source file
          Documentation/keys.txt.

   /proc/[pid]/attr/socketcreate (since Linux 2.6.18)
          If a process writes a  security  context  into  this  file,  all
          subsequently created sockets will be labeled with this context.

   /proc/[pid]/autogroup (since Linux 2.6.38)
          See sched(7).

   /proc/[pid]/auxv (since 2.6.0-test7)
          This  contains  the  contents of the ELF interpreter information
          passed to the process at exec time.  The format is one  unsigned
          long  ID  plus one unsigned long value for each entry.  The last
          entry contains two zeros.  See also getauxval(3).

          Permission to access this file is governed by  a  ptrace  access
          mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/cgroup (since Linux 2.6.24)
          See cgroups(7).

   /proc/[pid]/clear_refs (since Linux 2.6.22)

          This  is  a  write-only  file,  writable  only  by  owner of the
          process.

          The following values may be written to the file:

          1 (since Linux 2.6.22)
                 Reset the PG_Referenced and ACCESSED/YOUNG bits  for  all
                 the  pages  associated  with the process.  (Before kernel
                 2.6.32, writing any nonzero value to this file  had  this
                 effect.)

          2 (since Linux 2.6.32)
                 Reset  the  PG_Referenced and ACCESSED/YOUNG bits for all
                 anonymous pages associated with the process.

          3 (since Linux 2.6.32)
                 Reset the PG_Referenced and ACCESSED/YOUNG bits  for  all
                 file-mapped pages associated with the process.

          Clearing  the  PG_Referenced  and ACCESSED/YOUNG bits provides a
          method to measure approximately how much  memory  a  process  is
          using.  One first inspects the values in the "Referenced" fields
          for the VMAs shown in /proc/[pid]/smaps to get an  idea  of  the
          memory   footprint   of   the  process.   One  then  clears  the
          PG_Referenced and ACCESSED/YOUNG bits and, after  some  measured
          time   interval,   once   again   inspects  the  values  in  the
          "Referenced" fields to get an  idea  of  the  change  in  memory
          footprint  of  the process during the measured interval.  If one
          is interested only in inspecting  the  selected  mapping  types,
          then the value 2 or 3 can be used instead of 1.

          Further values can be written to affect different properties:

          4 (since Linux 3.11)
                 Clear  the  soft-dirty  bit  for all the pages associated
                 with the process.  This  is  used  (in  conjunction  with
                 /proc/[pid]/pagemap) by the check-point restore system to
                 discover which pages of a process have been dirtied since
                 the file /proc/[pid]/clear_refs was written to.

          5 (since Linux 4.0)
                 Reset  the  peak resident set size ("high water mark") to
                 the process's current resident set size value.

          Writing any value to  /proc/[pid]/clear_refs  other  than  those
          listed above has no effect.

          The   /proc/[pid]/clear_refs   file   is  present  only  if  the
          CONFIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

   /proc/[pid]/cmdline
          This read-only file holds the  complete  command  line  for  the
          process,  unless  the  process is a zombie.  In the latter case,
          there is nothing in this file: that is, a read on this file will
          return  0 characters.  The command-line arguments appear in this
          file as a set of strings separated by null bytes ('\0'), with  a
          further null byte after the last string.

   /proc/[pid]/comm (since Linux 2.6.33)
          This  file exposes the process's comm value---that is, the command
          name associated with the process.  Different threads in the same
          process   may   have   different  comm  values,  accessible  via
          /proc/[pid]/task/[tid]/comm.   A  thread  may  modify  its  comm
          value,  or  that of any of other thread in the same thread group
          (see the discussion of CLONE_THREAD in clone(2)), by writing  to
          the   file   /proc/self/task/[tid]/comm.   Strings  longer  than
          TASK_COMM_LEN (16) characters are silently truncated.

          This file provides a superset of the  prctl(2)  PR_SET_NAME  and
          PR_GET_NAME operations, and is employed by pthread_setname_np(3)
          when used to rename threads other than the caller.

   /proc/[pid]/coredump_filter (since Linux 2.6.23)
          See core(5).

   /proc/[pid]/cpuset (since Linux 2.6.12)
          See cpuset(7).

   /proc/[pid]/cwd
          This is a symbolic link to the current working directory of  the
          process.   To  find out the current working directory of process
          20, for instance, you can do this:

              $ cd /proc/20/cwd; /bin/pwd

          Note that the pwd command is often a shell built-in,  and  might
          not work properly.  In bash(1), you may use pwd -P.

          In  a  multithreaded process, the contents of this symbolic link
          are not available if the  main  thread  has  already  terminated
          (typically by calling pthread_exit(3)).

          Permission  to  dereference  or read (readlink(2)) this symbolic
          link    is    governed    by    a     ptrace     access     mode
          PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/environ
          This file contains the environment for the process.  The entries
          are separated by null bytes ('\0'), and there may be a null byte
          at  the  end.   Thus, to print out the environment of process 1,
          you would do:

              $ strings /proc/1/environ

          Permission to access this file is governed by  a  ptrace  access
          mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/exe
          Under  Linux  2.2  and  later,  this  file  is  a  symbolic link
          containing the actual pathname of the  executed  command.   This
          symbolic  link  can be dereferenced normally; attempting to open
          it will open the executable.  You can even type  /proc/[pid]/exe
          to  run another copy of the same executable that is being run by
          process [pid].  If the pathname has been unlinked, the  symbolic
          link  will  contain  the  string  '(deleted)'  appended  to  the
          original pathname.  In a multithreaded process, the contents  of
          this  symbolic  link  are  not  available if the main thread has
          already terminated (typically by calling pthread_exit(3)).

          Permission to dereference or read  (readlink(2))  this  symbolic
          link     is     governed     by    a    ptrace    access    mode
          PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

          Under Linux 2.0 and earlier, /proc/[pid]/exe is a pointer to the
          binary  which  was  executed, and appears as a symbolic link.  A
          readlink(2) call on this file under Linux 2.0 returns  a  string
          in the format:

              [device]:inode

          For  example, [0301]:1502 would be inode 1502 on device major 03
          (IDE, MFM, etc. drives) minor 01 (first partition on  the  first
          drive).

          find(1) with the -inum option can be used to locate the file.

   /proc/[pid]/fd/
          This  is a subdirectory containing one entry for each file which
          the process has open, named by its file descriptor, and which is
          a  symbolic link to the actual file.  Thus, 0 is standard input,
          1 standard output, 2 standard error, and so on.

          For file descriptors for pipes and sockets, the entries will  be
          symbolic links whose content is the file type with the inode.  A
          readlink(2) call on this file returns a string in the format:

              type:[inode]

          For example, socket:[2248868] will be a socket and its inode  is
          2248868.   For  sockets,  that  inode  can  be used to find more
          information in one of the files under /proc/net/.

          For file descriptors that have  no  corresponding  inode  (e.g.,
          file   descriptors   produced  by  epoll_create(2),  eventfd(2),
          inotify_init(2), signalfd(2), and timerfd(2)), the entry will be
          a symbolic link with contents of the form

              anon_inode:<file-type>

          In some cases, the file-type is surrounded by square brackets.

          For  example, an epoll file descriptor will have a symbolic link
          whose content is the string anon_inode:[eventpoll].

          In a multithreaded process, the contents of this  directory  are
          not   available  if  the  main  thread  has  already  terminated
          (typically by calling pthread_exit(3)).

          Programs that will take a filename as a  command-line  argument,
          but  will  not  take input from standard input if no argument is
          supplied, or that write  to  a  file  named  as  a  command-line
          argument,  but  will not send their output to standard output if
          no argument  is  supplied,  can  nevertheless  be  made  to  use
          standard  input  or  standard  out  using  /proc/[pid]/fd.   For
          example, assuming that -i is the flag designating an input  file
          and -o is the flag designating an output file:

              $ foobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...

          and you have a working filter.

          /proc/self/fd/N  is  approximately the same as /dev/fd/N in some
          UNIX  and  UNIX-like  systems.   Most  Linux   MAKEDEV   scripts
          symbolically link /dev/fd to /proc/self/fd, in fact.

          Most systems provide symbolic links /dev/stdin, /dev/stdout, and
          /dev/stderr, which respectively link to the files 0, 1, and 2 in
          /proc/self/fd.   Thus the example command above could be written
          as:

              $ foobar -i /dev/stdin -o /dev/stdout ...

          Permission to dereference or  read  (readlink(2))  the  symbolic
          links  in  this  directory  is  governed by a ptrace access mode
          PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/fdinfo/ (since Linux 2.6.22)
          This is a subdirectory containing one entry for each file  which
          the  process  has open, named by its file descriptor.  The files
          in this directory are readable only by the owner of the process.
          The  contents  of  each  file  can be read to obtain information
          about the corresponding file descriptor.  The content depends on
          the   type  of  file  referred  to  by  the  corresponding  file
          descriptor.

          For regular files and directories, we see something like:

              $ cat /proc/12015/fdinfo/4
              pos:    1000
              flags:  01002002
              mnt_id: 21

          The fields are as follows:

          pos    This is a decimal number showing the file offset.

          flags  This is an octal number that  displays  the  file  access
                 mode  and file status flags (see open(2)).  If the close-
                 on-exec file descriptor flag is set, then flags will also
                 include the value O_CLOEXEC.

                 Before  Linux  3.1,  this field incorrectly displayed the
                 setting of O_CLOEXEC at the time  the  file  was  opened,
                 rather  than  the  current  setting  of the close-on-exec
                 flag.

          mnt_id This field, present since Linux 3.15, is the  ID  of  the
                 mount point containing this file.  See the description of
                 /proc/[pid]/mountinfo.

          For eventfd file descriptors (see  eventfd(2)),  we  see  (since
          Linux 3.8) the following fields:

              pos: 0
              flags:    02
              mnt_id:   10
              eventfd-count:               40

          eventfd-count  is  the  current value of the eventfd counter, in
          hexadecimal.

          For epoll file descriptors (see epoll(7)), we see  (since  Linux
          3.8) the following fields:

              pos: 0
              flags:    02
              mnt_id:   10
              tfd:        9 events:       19 data: 74253d2500000009
              tfd:        7 events:       19 data: 74253d2500000007

          Each  of  the  lines  beginning  tfd  describes  one of the file
          descriptors being monitored via the epoll file  descriptor  (see
          epoll_ctl(2)  for some details).  The tfd field is the number of
          the file descriptor.  The events field is a hexadecimal mask  of
          the  events  being monitored for this file descriptor.  The data
          field is the data value associated with this file descriptor.

          For signalfd file descriptors (see signalfd(2)), we  see  (since
          Linux 3.8) the following fields:

              pos: 0
              flags:    02
              mnt_id:   10
              sigmask:  0000000000000006

          sigmask is the hexadecimal mask of signals that are accepted via
          this signalfd file descriptor.  (In this example, bits 2  and  3
          are  set,  corresponding  to the signals SIGINT and SIGQUIT; see
          signal(7).)

          For inotify file descriptors (see  inotify(7)),  we  see  (since
          Linux 3.8) the following fields:

              pos: 0
              flags:    00
              mnt_id:   11
              inotify wd:2 ino:7ef82a sdev:800001 mask:800afff ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:2af87e00220ffd73
              inotify wd:1 ino:192627 sdev:800001 mask:800afff ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:27261900802dfd73

          Each  of the lines beginning with "inotify" displays information
          about one file or directory that is being monitored.  The fields
          in this line are as follows:

          wd     A watch descriptor number (in decimal).

          ino    The inode number of the target file (in hexadecimal).

          sdev   The  ID  of  the device where the target file resides (in
                 hexadecimal).

          mask   The mask of events being monitored for  the  target  file
                 (in hexadecimal).

          If  the  kernel was built with exportfs support, the path to the
          target file is exposed as a file handle, via  three  hexadecimal
          fields: fhandle-bytes, fhandle-type, and f_handle.

          For  fanotify  file descriptors (see fanotify(7)), we see (since
          Linux 3.8) the following fields:

              pos: 0
              flags:    02
              mnt_id:   11
              fanotify flags:0 event-flags:88002
              fanotify ino:19264f sdev:800001 mflags:0 mask:1 ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:4f261900a82dfd73

          The fourth line displays information defined when  the  fanotify
          group was created via fanotify_init(2):

          flags  The  flags  argument given to fanotify_init(2) (expressed
                 in hexadecimal).

          event-flags
                 The  event_f_flags  argument  given  to  fanotify_init(2)
                 (expressed in hexadecimal).

          Each  additional  line  shown  in  the file contains information
          about one of the marks in the fanotify  group.   Most  of  these
          fields are as for inotify, except:

          mflags The   flags   associated  with  the  mark  (expressed  in
                 hexadecimal).

          mask   The events mask for this mark (expressed in hexadecimal).

          ignored_mask
                 The mask  of  events  that  are  ignored  for  this  mark
                 (expressed in hexadecimal).

          For details on these fields, see fanotify_mark(2).

   /proc/[pid]/io (since kernel 2.6.20)
          This file contains I/O statistics for the process, for example:

              # cat /proc/3828/io
              rchar: 323934931
              wchar: 323929600
              syscr: 632687
              syscw: 632675
              read_bytes: 0
              write_bytes: 323932160
              cancelled_write_bytes: 0

          The fields are as follows:

          rchar: characters read
                 The number of bytes which this task has caused to be read
                 from storage.  This is simply the sum of bytes which this
                 process  passed  to read(2) and similar system calls.  It
                 includes things such as terminal I/O and is unaffected by
                 whether or not actual physical disk I/O was required (the
                 read might have been satisfied from pagecache).

          wchar: characters written
                 The number of bytes which this task has caused, or  shall
                 cause  to be written to disk.  Similar caveats apply here
                 as with rchar.

          syscr: read syscalls
                 Attempt to count the number of read  I/O  operations---that
                 is, system calls such as read(2) and pread(2).

          syscw: write syscalls
                 Attempt  to count the number of write I/O operations---that
                 is, system calls such as write(2) and pwrite(2).

          read_bytes: bytes read
                 Attempt to count the number of bytes which  this  process
                 really  did  cause  to be fetched from the storage layer.
                 This is accurate for block-backed filesystems.

          write_bytes: bytes written
                 Attempt to count the number of bytes which  this  process
                 caused to be sent to the storage layer.

          cancelled_write_bytes:
                 The big inaccuracy here is truncate.  If a process writes
                 1MB to a file and then deletes the file, it will in  fact
                 perform  no writeout.  But it will have been accounted as
                 having caused 1MB of write.  In other words:  this  field
                 represents  the number of bytes which this process caused
                 to not happen, by truncating pagecache.  A task can cause
                 "negative"  I/O  too.   If this task truncates some dirty
                 pagecache, some I/O which another task has been accounted
                 for (in its write_bytes) will not be happening.

          Note:  In  the  current implementation, things are a bit racy on
          32-bit systems: if process A reads  process  B's  /proc/[pid]/io
          while  process  B  is  updating  one  of  these 64-bit counters,
          process A could see an intermediate result.

          Permission to access this file is governed by  a  ptrace  access
          mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/gid_map (since Linux 3.5)
          See user_namespaces(7).

   /proc/[pid]/limits (since Linux 2.6.24)
          This  file  displays  the  soft  limit, hard limit, and units of
          measurement for each  of  the  process's  resource  limits  (see
          getrlimit(2)).   Up  to and including Linux 2.6.35, this file is
          protected to allow reading only by the real UID of the  process.
          Since  Linux  2.6.36,  this file is readable by all users on the
          system.

   /proc/[pid]/map_files/ (since kernel 3.3)
          This subdirectory  contains  entries  corresponding  to  memory-
          mapped  files (see mmap(2)).  Entries are named by memory region
          start and end address pair (expressed as  hexadecimal  numbers),
          and  are symbolic links to the mapped files themselves.  Here is
          an example, with the output wrapped and reformatted to fit on an
          80-column display:

              # ls -l /proc/self/map_files/
              lr--------. 1 root root 64 Apr 16 21:31
                          3252e00000-3252e20000 -> /usr/lib64/ld-2.15.so
              ...

          Although  these entries are present for memory regions that were
          mapped with the MAP_FILE flag, the way anonymous  shared  memory
          (regions  created  with  the  MAP_ANON  |  MAP_SHARED  flags) is
          implemented in Linux means that such regions also appear on this
          directory.   Here  is  an  example  where the target file is the
          deleted /dev/zero one:

              lrw-------. 1 root root 64 Apr 16 21:33
                          7fc075d2f000-7fc075e6f000 -> /dev/zero (deleted)

          This directory appears  only  if  the  CONFIG_CHECKPOINT_RESTORE
          kernel    configuration    option    is    enabled.    Privilege
          (CAP_SYS_ADMIN)  is  required  to  view  the  contents  of  this
          directory.

   /proc/[pid]/maps
          A  file containing the currently mapped memory regions and their
          access permissions.  See mmap(2) for  some  further  information
          about memory mappings.

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

          The format of the file is:

   address           perms offset  dev   inode       pathname
   00400000-00452000 r-xp 00000000 08:02 173521      /usr/bin/dbus-daemon
   00651000-00652000 r--p 00051000 08:02 173521      /usr/bin/dbus-daemon
   00652000-00655000 rw-p 00052000 08:02 173521      /usr/bin/dbus-daemon
   00e03000-00e24000 rw-p 00000000 00:00 0           [heap]
   00e24000-011f7000 rw-p 00000000 00:00 0           [heap]
   ...
   35b1800000-35b1820000 r-xp 00000000 08:02 135522  /usr/lib64/ld-2.15.so
   35b1a1f000-35b1a20000 r--p 0001f000 08:02 135522  /usr/lib64/ld-2.15.so
   35b1a20000-35b1a21000 rw-p 00020000 08:02 135522  /usr/lib64/ld-2.15.so
   35b1a21000-35b1a22000 rw-p 00000000 00:00 0
   35b1c00000-35b1dac000 r-xp 00000000 08:02 135870  /usr/lib64/libc-2.15.so
   35b1dac000-35b1fac000 ---p 001ac000 08:02 135870  /usr/lib64/libc-2.15.so
   35b1fac000-35b1fb0000 r--p 001ac000 08:02 135870  /usr/lib64/libc-2.15.so
   35b1fb0000-35b1fb2000 rw-p 001b0000 08:02 135870  /usr/lib64/libc-2.15.so
   ...
   f2c6ff8c000-7f2c7078c000 rw-p 00000000 00:00 0    [stack:986]
   ...
   7fffb2c0d000-7fffb2c2e000 rw-p 00000000 00:00 0   [stack]
   7fffb2d48000-7fffb2d49000 r-xp 00000000 00:00 0   [vdso]

          The address field is the address space in the process  that  the
          mapping occupies.  The perms field is a set of permissions:

               r = read
               w = write
               x = execute
               s = shared
               p = private (copy on write)

          The  offset  field  is the offset into the file/whatever; dev is
          the device (major:minor); inode is the inode on that device.   0
          indicates that no inode is associated with the memory region, as
          would be the case with BSS (uninitialized data).

          The pathname field will usually be the file that is backing  the
          mapping.   For  ELF  files,  you  can easily coordinate with the
          offset field by looking at the Offset field in the  ELF  program
          headers (readelf -l).

          There are additional helpful pseudo-paths:

               [stack]
                      The  initial  process's  (also  known  as  the  main
                      thread's) stack.

               [stack:<tid>] (since Linux 3.4)
                      A thread's stack (where the <tid> is a  thread  ID).
                      It corresponds to the /proc/[pid]/task/[tid]/ path.

               [vdso] The virtual dynamically linked shared object.

               [heap] The process's heap.

          If  the pathname field is blank, this is an anonymous mapping as
          obtained via mmap(2).  There is no easy way to  coordinate  this
          back  to a process's source, short of running it through gdb(1),
          strace(1), or similar.

          Under Linux 2.0, there is no field giving pathname.

   /proc/[pid]/mem
          This file can be used to access the pages of a process's  memory
          through open(2), read(2), and lseek(2).

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

   /proc/[pid]/mountinfo (since Linux 2.6.26)
          This  file  contains  information  about  mount  points  in  the
          process's   mount   namespace   (see  mount_namespaces(7)).   It
          supplies various information (e.g., propagation state,  root  of
          mount for bind mounts, identifier for each mount and its parent)
          that is missing from the (older)  /proc/[pid]/mounts  file,  and
          fixes   various   other   problems   with   that   file   (e.g.,
          nonextensibility, failure to distinguish per-mount  versus  per-
          superblock options).

          The file contains lines of the form:

          36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
          (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)

          The  numbers  in  parentheses  are  labels  for the descriptions
          below:

          (1)  mount ID: a unique ID for the mount (may  be  reused  after
               umount(2)).

          (2)  parent  ID:  the ID of the parent mount (or of self for the
               top of the mount tree).

          (3)  major:minor:  the  value  of  st_dev  for  files  on   this
               filesystem (see stat(2)).

          (4)  root: the pathname of the directory in the filesystem which
               forms the root of this mount.

          (5)  mount point: the pathname of the mount  point  relative  to
               the process's root directory.

          (6)  mount options: per-mount options.

          (7)  optional   fields:   zero   or  more  fields  of  the  form
               "tag[:value]"; see below.

          (8)  separator: the end of the optional fields is  marked  by  a
               single hyphen.

          (9)  filesystem   type:   the   filesystem   type  in  the  form
               "type[.subtype]".

          (10) mount source: filesystem-specific information or "none".

          (11) super options: per-superblock options.

          Currently, the possible  optional  fields  are  shared,  master,
          propagate_from,  and  unbindable.  See mount_namespaces(7) for a
          description  of  these  fields.   Parsers  should   ignore   all
          unrecognized optional fields.

          For    more    information    on    mount    propagation    see:
          Documentation/filesystems/sharedsubtree.txt in the Linux  kernel
          source tree.

   /proc/[pid]/mounts (since Linux 2.4.19)
          This  file  lists  all  the filesystems currently mounted in the
          process's mount namespace (see mount_namespaces(7)).  The format
          of this file is documented in fstab(5).

          Since  kernel  version  2.6.15,  this  file  is  pollable: after
          opening the file for reading, a change in  this  file  (i.e.,  a
          filesystem  mount  or unmount) causes select(2) to mark the file
          descriptor as having an exceptional condition, and  poll(2)  and
          epoll_wait(2)   mark   the  file  as  having  a  priority  event
          (POLLPRI).  (Before Linux 2.6.30, a  change  in  this  file  was
          indicated  by  the  file descriptor being marked as readable for
          select(2), and being marked as having  an  error  condition  for
          poll(2) and epoll_wait(2).)

   /proc/[pid]/mountstats (since Linux 2.6.17)
          This   file   exports   information  (statistics,  configuration
          information) about the  mount  points  in  the  process's  mount
          namespace  (see  mount_namespaces(7)).   Lines in this file have
          the form:

          device /dev/sda7 mounted on /home with fstype ext3 [statistics]
          (       1      )            ( 2 )             (3 ) (4)

          The fields in each line are:

          (1)  The name of the mounted device (or "nodevice" if  there  is
               no corresponding device).

          (2)  The mount point within the filesystem tree.

          (3)  The filesystem type.

          (4)  Optional    statistics   and   configuration   information.
               Currently (as at Linux 2.6.26), only NFS filesystems export
               information via this field.

          This file is readable only by the owner of the process.

   /proc/[pid]/net " (since Linux 2.6.25)"
          See the description of /proc/net.

   /proc/[pid]/ns/ (since Linux 3.0)
          This  is  a subdirectory containing one entry for each namespace
          that  supports  being  manipulated  by   setns(2).    For   more
          information, see namespaces(7).

   /proc/[pid]/numa_maps (since Linux 2.6.14)
          See numa(7).

   /proc/[pid]/oom_adj (since Linux 2.6.11)
          This  file  can be used to adjust the score used to select which
          process should be killed in an  out-of-memory  (OOM)  situation.
          The  kernel  uses  this  value  for a bit-shift operation of the
          process's oom_score value: valid values are in the range -16  to
          +15,  plus  the  special  value  -17, which disables OOM-killing
          altogether for this process.  A  positive  score  increases  the
          likelihood  of  this  process  being killed by the OOM-killer; a
          negative score decreases the likelihood.

          The default value for this file is 0; a new process inherits its
          parent's   oom_adj   setting.   A  process  must  be  privileged
          (CAP_SYS_RESOURCE) to update this file.

          Since Linux 2.6.36, use of this file is deprecated in  favor  of
          /proc/[pid]/oom_score_adj.

   /proc/[pid]/oom_score (since Linux 2.6.11)
          This  file  displays  the current score that the kernel gives to
          this process for the purpose of selecting a process for the OOM-
          killer.  A higher score means that the process is more likely to
          be selected by the OOM-killer.  The basis for this score is  the
          amount  of  memory  used  by  the process, with increases (+) or
          decreases (-) for factors including:

          * whether the process creates a lot of  children  using  fork(2)
            (+);

          * whether  the process has been running a long time, or has used
            a lot of CPU time (-);

          * whether the process has a low nice value (i.e., > 0) (+);

          * whether the process is privileged (-); and

          * whether the process is making direct hardware access (-).

          The oom_score also reflects  the  adjustment  specified  by  the
          oom_score_adj or oom_adj setting for the process.

   /proc/[pid]/oom_score_adj (since Linux 2.6.36)
          This  file  can  be used to adjust the badness heuristic used to
          select which process gets killed in out-of-memory conditions.

          The badness heuristic assigns a value  to  each  candidate  task
          ranging  from  0 (never kill) to 1000 (always kill) to determine
          which process is targeted.  The units are roughly  a  proportion
          along  that  range  of  allowed  memory the process may allocate
          from, based on an estimation of its current memory and swap use.
          For  example, if a task is using all allowed memory, its badness
          score will be 1000.  If it is using half of its allowed  memory,
          its score will be 500.

          There  is  an  additional  factor included in the badness score:
          root processes are given 3% extra memory over other tasks.

          The amount of "allowed" memory depends on the context  in  which
          the  OOM-killer was called.  If it is due to the memory assigned
          to the allocating task's cpuset  being  exhausted,  the  allowed
          memory  represents  the set of mems assigned to that cpuset (see
          cpuset(7)).  If  it  is  due  to  a  mempolicy's  node(s)  being
          exhausted,  the  allowed  memory represents the set of mempolicy
          nodes.  If it is due to a memory limit  (or  swap  limit)  being
          reached,  the allowed memory is that configured limit.  Finally,
          if it is due to the entire  system  being  out  of  memory,  the
          allowed memory represents all allocatable resources.

          The  value of oom_score_adj is added to the badness score before
          it is used to determine which task to kill.   Acceptable  values
          range     from     -1000     (OOM_SCORE_ADJ_MIN)     to    +1000
          (OOM_SCORE_ADJ_MAX).  This allows  user  space  to  control  the
          preference  for  OOM-killing,  ranging  from always preferring a
          certain task or completely disabling it from OOM  killing.   The
          lowest  possible  value,  -1000, is equivalent to disabling OOM-
          killing entirely for that task, since it will  always  report  a
          badness score of 0.

          Consequently,  it  is  very  simple for user space to define the
          amount  of  memory  to  consider  for  each  task.   Setting   a
          oom_score_adj  value of +500, for example, is roughly equivalent
          to allowing the remainder of  tasks  sharing  the  same  system,
          cpuset,  mempolicy,  or  memory  controller  resources to use at
          least 50% more memory.  A value of  -500,  on  the  other  hand,
          would  be  roughly  equivalent  to discounting 50% of the task's
          allowed memory from being  considered  as  scoring  against  the
          task.

          For    backward    compatibility    with    previous    kernels,
          /proc/[pid]/oom_adj can still be used to tune the badness score.
          Its value is scaled linearly with oom_score_adj.

          Writing to /proc/[pid]/oom_score_adj or /proc/[pid]/oom_adj will
          change the other with its scaled value.

   /proc/[pid]/pagemap (since Linux 2.6.25)
          This file shows the mapping of each  of  the  process's  virtual
          pages  into  physical page frames or swap area.  It contains one
          64-bit value for  each  virtual  page,  with  the  bits  set  as
          follows:

               63     If set, the page is present in RAM.

               62     If set, the page is in swap space

               61 (since Linux 3.5)
                      The page is a file-mapped page or a shared anonymous
                      page.

               60-56 (since Linux 3.11)
                      Zero

               55 (Since Linux 3.11)
                      PTE  is  soft-dirty  (see  the  kernel  source  file
                      Documentation/vm/soft-dirty.txt).

               54-0   If  the  page is present in RAM (bit 63), then these
                      bits provide the page frame  number,  which  can  be
                      used to index /proc/kpageflags and /proc/kpagecount.
                      If the page is present in swap (bit 62),  then  bits
                      4-0  give  the  swap  type, and bits 54-5 encode the
                      swap offset.

          Before Linux 3.11, bits 60-55 were used to encode the base-2 log
          of the page size.

          To  employ /proc/[pid]/pagemap efficiently, use /proc/[pid]/maps
          to determine which areas of memory are actually mapped and  seek
          to skip over unmapped regions.

          The   /proc/[pid]/pagemap   file   is   present   only   if  the
          CONFIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

          Permission to access this file is governed by  a  ptrace  access
          mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/personality (since Linux 2.6.28)
          This  read-only  file exposes the process's execution domain, as
          set by personality(2).  The value is  displayed  in  hexadecimal
          notation.

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

   /proc/[pid]/root
          UNIX and Linux support the idea of a  per-process  root  of  the
          filesystem,  set  by  the chroot(2) system call.  This file is a
          symbolic link that points to the process's root  directory,  and
          behaves in the same way as exe, and fd/*.

          Note  however  that this file is not merely a symbolic link.  It
          provides the same view of the filesystem  (including  namespaces
          and  the  set  of per-process mounts) as the process itself.  An
          example illustrates this point.  In one  terminal,  we  start  a
          shell  in  new  user  and mount namespaces, and in that shell we
          create some new mount points:

              $ PS1='sh1# ' unshare -Urnm
              sh1# mount -t tmpfs tmpfs /etc  # Mount empty tmpfs at /etc
              sh1# mount --bind /usr /dev     # Mount /usr at /dev
              sh1# echo $$
              27123

          In a second terminal window, in the initial mount namespace,  we
          look  at the contents of the corresponding mounts in the initial
          and new namespaces:

              $ PS1='sh2# ' sudo sh
              sh2# ls /etc | wc -l                  # In initial NS
              309
              sh2# ls /proc/27123/root/etc | wc -l  # /etc in other NS
              0                                     # The empty tmpfs dir
              sh2# ls /dev | wc -l                  # In initial NS
              205
              sh2# ls /proc/27123/root/dev | wc -l  # /dev in other NS
              11                                    # Actually bind
                                                    # mounted to /usr
              sh2# ls /usr | wc -l                  # /usr in initial NS
              11

          In a multithreaded process, the contents of the /proc/[pid]/root
          symbolic  link  are not available if the main thread has already
          terminated (typically by calling pthread_exit(3)).

          Permission to dereference or read  (readlink(2))  this  symbolic
          link     is     governed     by    a    ptrace    access    mode
          PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/[pid]/seccomp (Linux 2.6.12 to 2.6.22)
          This file can be used to read and change  the  process's  secure
          computing  (seccomp)  mode  setting.  It contains the value 0 if
          the process is not in seccomp mode, and 1 if the process  is  in
          strict  seccomp  mode  (see seccomp(2)).  Writing 1 to this file
          places  the  process  irreversibly  in  strict   seccomp   mode.
          (Further  attempts  to  write  to  the  file fail with the EPERM
          error.)

          In Linux 2.6.23, this file went away,  to  be  replaced  by  the
          prctl(2) PR_GET_SECCOMP and PR_SET_SECCOMP operations (and later
          by seccomp(2) and the Seccomp field in /proc/[pid]/status).

   /proc/[pid]/seccomp (from Linux 2.6.12 to 2.6.22)
          Read/set the  seccomp  mode  for  the  process.   If  this  file
          contains  the  value zero, seccomp mode is not enabled.  Writing
          the value 1 to this file (irreversibly) places  the  process  in
          seccomp  mode:  the  only  permitted  system  calls are read(2),
          write(2), _exit(2), and sigreturn(2).  This file  went  away  in
          Linux   2.6.23,   when  it  was  replaced  by  a  prctl(2)-based
          mechanism.

   /proc/[pid]/setgroups (since Linux 3.19)
          See user_namespaces(7).

   /proc/[pid]/smaps (since Linux 2.6.14)
          This file shows memory consumption for  each  of  the  process's
          mappings.  (The pmap(1) command displays similar information, in
          a form that may be easier for parsing.)  For each mapping  there
          is a series of lines such as the following:

              00400000-0048a000 r-xp 00000000 fd:03 960637       /bin/bash
              Size:                552 kB
              Rss:                 460 kB
              Pss:                 100 kB
              Shared_Clean:        452 kB
              Shared_Dirty:          0 kB
              Private_Clean:         8 kB
              Private_Dirty:         0 kB
              Referenced:          460 kB
              Anonymous:             0 kB
              AnonHugePages:         0 kB
              ShmemHugePages:        0 kB
              ShmemPmdMapped:        0 kB
              Swap:                  0 kB
              KernelPageSize:        4 kB
              MMUPageSize:           4 kB
              KernelPageSize:        4 kB
              MMUPageSize:           4 kB
              Locked:                0 kB
              ProtectionKey:         0
              VmFlags: rd ex mr mw me dw

          The  first  of  these  lines  shows  the  same information as is
          displayed for the mapping in  /proc/[pid]/maps.   The  following
          lines  show  the  size of the mapping, the amount of the mapping
          that  is  currently  resident  in  RAM  ("Rss"),  the  process's
          proportional  share of this mapping ("Pss"), the number of clean
          and dirty shared pages in the mapping, and the number  of  clean
          and  dirty private pages in the mapping.  "Referenced" indicates
          the amount of memory currently marked as referenced or accessed.
          "Anonymous"  shows  the amount of memory that does not belong to
          any file.  "Swap" shows how much  would-be-anonymous  memory  is
          also used, but out on swap.

          The  "KernelPageSize" line (available since Linux 2.6.29) is the
          page size used by the kernel to back the  virtual  memory  area.
          This  matches the size used by the MMU in the majority of cases.
          However, one counter-example occurs on PPC64 kernels  whereby  a
          kernel  using  64kB  as a base page size may still use 4kB pages
          for the  MMU  on  older  processors.   To  distinguish  the  two
          attributes,  the  "MMUPageSize" line (also available since Linux
          2.6.29) reports the page size used by the MMU.

          The "Locked" indicates whether the mapping is locked  in  memory
          or not.

          The  "ProtectionKey"  line  (available  since  Linux 4.9, on x86
          only)  contains  the  memory  protection  key   (see   pkeys(7))
          associated  with the virtual memory area.  This entry is present
          only    if     the     kernel     was     built     with     the
          CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS configuration option.

          The  "VmFlags"  line  (available since Linux 3.8) represents the
          kernel flags associated with the virtual  memory  area,  encoded
          using the following two-letter codes:

              rd  - readable
              wr  - writable
              ex  - executable
              sh  - shared
              mr  - may read
              mw  - may write
              me  - may execute
              ms  - may share
              gd  - stack segment grows down
              pf  - pure PFN range
              dw  - disabled write to the mapped file
              lo  - pages are locked in memory
              io  - memory mapped I/O area
              sr  - sequential read advise provided
              rr  - random read advise provided
              dc  - do not copy area on fork
              de  - do not expand area on remapping
              ac  - area is accountable
              nr  - swap space is not reserved for the area
              ht  - area uses huge tlb pages
              nl  - non-linear mapping
              ar  - architecture specific flag
              dd  - do not include area into core dump
              sd  - soft-dirty flag
              mm  - mixed map area
              hg  - huge page advise flag
              nh  - no-huge page advise flag
              mg  - mergeable advise flag

          "ProtectionKey"  field  contains  the memory protection key (see
          pkeys(5)) associated with the virtual memory area.  Present only
          if       the       kernel      was      built      with      the
          CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS  configuration   option.
          (since Linux 4.6)

          The    /proc/[pid]/smaps   file   is   present   only   if   the
          CONFIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

   /proc/[pid]/stack (since Linux 2.6.29)
          This file provides a symbolic trace of  the  function  calls  in
          this  process's kernel stack.  This file is provided only if the
          kernel  was  built  with  the  CONFIG_STACKTRACE   configuration
          option.

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

   /proc/[pid]/stat
          Status information about the process.  This is  used  by  ps(1).
          It is defined in the kernel source file fs/proc/array.c.

          The   fields,  in  order,  with  their  proper  scanf(3)  format
          specifiers, are listed below.  Whether or not certain  of  these
          fields  display valid information is governed by a ptrace access
          mode PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT check (refer
          to ptrace(2)).  If the check denies access, then the field value
          is displayed as 0.  The affected fields are indicated  with  the
          marking [PT].

          (1) pid  %d
                    The process ID.

          (2) comm  %s
                    The  filename of the executable, in parentheses.  This
                    is visible whether or not the  executable  is  swapped
                    out.

          (3) state  %c
                    One  of  the  following characters, indicating process
                    state:

                    R  Running

                    S  Sleeping in an interruptible wait

                    D  Waiting in uninterruptible disk sleep

                    Z  Zombie

                    T  Stopped (on a  signal)  or  (before  Linux  2.6.33)
                       trace stopped

                    t  Tracing stop (Linux 2.6.33 onward)

                    W  Paging (only before Linux 2.6.0)

                    X  Dead (from Linux 2.6.0 onward)

                    x  Dead (Linux 2.6.33 to 3.13 only)

                    K  Wakekill (Linux 2.6.33 to 3.13 only)

                    W  Waking (Linux 2.6.33 to 3.13 only)

                    P  Parked (Linux 3.9 to 3.13 only)

          (4) ppid  %d
                    The PID of the parent of this process.

          (5) pgrp  %d
                    The process group ID of the process.

          (6) session  %d
                    The session ID of the process.

          (7) tty_nr  %d
                    The  controlling  terminal of the process.  (The minor
                    device number is contained in the combination of  bits
                    31  to  20  and  7 to 0; the major device number is in
                    bits 15 to 8.)

          (8) tpgid  %d
                    The  ID  of  the  foreground  process  group  of   the
                    controlling terminal of the process.

          (9) flags  %u
                    The  kernel  flags  word  of  the  process.   For  bit
                    meanings, see the PF_* defines  in  the  Linux  kernel
                    source  file include/linux/sched.h.  Details depend on
                    the kernel version.

                    The format for this field was %lu before Linux 2.6.

          (10) minflt  %lu
                    The number of minor faults the process has made  which
                    have not required loading a memory page from disk.

          (11) cminflt  %lu
                    The  number of minor faults that the process's waited-
                    for children have made.

          (12) majflt  %lu
                    The number of major faults the process has made  which
                    have required loading a memory page from disk.

          (13) cmajflt  %lu
                    The  number of major faults that the process's waited-
                    for children have made.

          (14) utime  %lu
                    Amount of time that this process has been scheduled in
                    user   mode,   measured  in  clock  ticks  (divide  by
                    sysconf(_SC_CLK_TCK)).   This  includes  guest   time,
                    guest_time  (time  spent  running  a  virtual CPU, see
                    below), so that applications that are not aware of the
                    guest  time  field  do  not  lose that time from their
                    calculations.

          (15) stime  %lu
                    Amount of time that this process has been scheduled in
                    kernel  mode,  measured  in  clock  ticks  (divide  by
                    sysconf(_SC_CLK_TCK)).

          (16) cutime  %ld
                    Amount of time that this process's waited-for children
                    have  been  scheduled  in user mode, measured in clock
                    ticks (divide  by  sysconf(_SC_CLK_TCK)).   (See  also
                    times(2).)   This  includes  guest  time,  cguest_time
                    (time spent running a virtual CPU, see below).

          (17) cstime  %ld
                    Amount of time that this process's waited-for children
                    have  been scheduled in kernel mode, measured in clock
                    ticks (divide by sysconf(_SC_CLK_TCK)).

          (18) priority  %ld
                    (Explanation for Linux 2.6) For  processes  running  a
                    real-time   scheduling   policy   (policy  below;  see
                    sched_setscheduler(2)), this is the negated scheduling
                    priority, minus one; that is, a number in the range -2
                    to -100, corresponding to real-time  priorities  1  to
                    99.   For  processes  running  under  a  non-real-time
                    scheduling  policy,  this  is  the  raw   nice   value
                    (setpriority(2))  as  represented  in the kernel.  The
                    kernel stores nice values as numbers in  the  range  0
                    (high)  to 39 (low), corresponding to the user-visible
                    nice range of -20 to 19.

                    Before Linux 2.6, this was a scaled value based on the
                    scheduler weighting given to this process.

          (19) nice  %ld
                    The  nice  value  (see setpriority(2)), a value in the
                    range 19 (low priority) to -20 (high priority).

          (20) num_threads  %ld
                    Number of threads in this process (since  Linux  2.6).
                    Before kernel 2.6, this field was hard coded to 0 as a
                    placeholder for an earlier removed field.

          (21) itrealvalue  %ld
                    The time in jiffies before the next SIGALRM is sent to
                    the  process  due  to an interval timer.  Since kernel
                    2.6.17, this field is no  longer  maintained,  and  is
                    hard coded as 0.

          (22) starttime  %llu
                    The  time  the  process started after system boot.  In
                    kernels before Linux 2.6, this value was expressed  in
                    jiffies.   Since  Linux 2.6, the value is expressed in
                    clock ticks (divide by sysconf(_SC_CLK_TCK)).

                    The format for this field was %lu before Linux 2.6.

          (23) vsize  %lu
                    Virtual memory size in bytes.

          (24) rss  %ld
                    Resident Set Size: number of pages the process has  in
                    real  memory.   This  is  just  the  pages which count
                    toward text, data, or  stack  space.   This  does  not
                    include pages which have not been demand-loaded in, or
                    which are swapped out.

          (25) rsslim  %lu
                    Current soft limit in bytes on the rss of the process;
                    see the description of RLIMIT_RSS in getrlimit(2).

          (26) startcode  %lu  [PT]
                    The address above which program text can run.

          (27) endcode  %lu  [PT]
                    The address below which program text can run.

          (28) startstack  %lu  [PT]
                    The address of the start (i.e., bottom) of the stack.

          (29) kstkesp  %lu  [PT]
                    The  current value of ESP (stack pointer), as found in
                    the kernel stack page for the process.

          (30) kstkeip  %lu  [PT]
                    The current EIP (instruction pointer).

          (31) signal  %lu
                    The bitmap of pending signals, displayed as a  decimal
                    number.    Obsolete,   because  it  does  not  provide
                    information     on     real-time     signals;      use
                    /proc/[pid]/status instead.

          (32) blocked  %lu
                    The  bitmap of blocked signals, displayed as a decimal
                    number.   Obsolete,  because  it  does   not   provide
                    information      on     real-time     signals;     use
                    /proc/[pid]/status instead.

          (33) sigignore  %lu
                    The bitmap of ignored signals, displayed as a  decimal
                    number.    Obsolete,   because  it  does  not  provide
                    information     on     real-time     signals;      use
                    /proc/[pid]/status instead.

          (34) sigcatch  %lu
                    The  bitmap  of caught signals, displayed as a decimal
                    number.   Obsolete,  because  it  does   not   provide
                    information      on     real-time     signals;     use
                    /proc/[pid]/status instead.

          (35) wchan  %lu  [PT]
                    This is the "channel" in which the process is waiting.
                    It  is  the  address of a location in the kernel where
                    the process is sleeping.  The  corresponding  symbolic
                    name can be found in /proc/[pid]/wchan.

          (36) nswap  %lu
                    Number of pages swapped (not maintained).

          (37) cnswap  %lu
                    Cumulative nswap for child processes (not maintained).

          (38) exit_signal  %d  (since Linux 2.1.22)
                    Signal to be sent to parent when we die.

          (39) processor  %d  (since Linux 2.2.8)
                    CPU number last executed on.

          (40) rt_priority  %u  (since Linux 2.5.19)
                    Real-time scheduling priority, a number in the range 1
                    to  99  for  processes  scheduled  under  a  real-time
                    policy,   or   0,  for  non-real-time  processes  (see
                    sched_setscheduler(2)).

          (41) policy  %u  (since Linux 2.5.19)
                    Scheduling policy (see sched_setscheduler(2)).  Decode
                    using the SCHED_* constants in linux/sched.h.

                    The format for this field was %lu before Linux 2.6.22.

          (42) delayacct_blkio_ticks  %llu  (since Linux 2.6.18)
                    Aggregated  block  I/O delays, measured in clock ticks
                    (centiseconds).

          (43) guest_time  %lu  (since Linux 2.6.24)
                    Guest time  of  the  process  (time  spent  running  a
                    virtual CPU for a guest operating system), measured in
                    clock ticks (divide by sysconf(_SC_CLK_TCK)).

          (44) cguest_time  %ld  (since Linux 2.6.24)
                    Guest time of  the  process's  children,  measured  in
                    clock ticks (divide by sysconf(_SC_CLK_TCK)).

          (45) start_data  %lu  (since Linux 3.3)  [PT]
                    Address    above   which   program   initialized   and
                    uninitialized (BSS) data are placed.

          (46) end_data  %lu  (since Linux 3.3)  [PT]
                    Address   below   which   program   initialized    and
                    uninitialized (BSS) data are placed.

          (47) start_brk  %lu  (since Linux 3.3)  [PT]
                    Address  above which program heap can be expanded with
                    brk(2).

          (48) arg_start  %lu  (since Linux 3.5)  [PT]
                    Address above  which  program  command-line  arguments
                    (argv) are placed.

          (49) arg_end  %lu  (since Linux 3.5)  [PT]
                    Address  below  program  command-line arguments (argv)
                    are placed.

          (50) env_start  %lu  (since Linux 3.5)  [PT]
                    Address above which program environment is placed.

          (51) env_end  %lu  (since Linux 3.5)  [PT]
                    Address below which program environment is placed.

          (52) exit_code  %d  (since Linux 3.5)  [PT]
                    The thread's exit  status  in  the  form  reported  by
                    waitpid(2).

   /proc/[pid]/statm
          Provides information about memory usage, measured in pages.  The
          columns are:

              size       (1) total program size
                         (same as VmSize in /proc/[pid]/status)
              resident   (2) resident set size
                         (same as VmRSS in /proc/[pid]/status)
              shared     (3) number of resident shared pages (i.e., backed by a file)
                         (same as RssFile+RssShmem in /proc/[pid]/status)
              text       (4) text (code)
              lib        (5) library (unused since Linux 2.6; always 0)
              data       (6) data + stack
              dt         (7) dirty pages (unused since Linux 2.6; always 0)

   /proc/[pid]/status
          Provides  much  of  the  information  in  /proc/[pid]/stat   and
          /proc/[pid]/statm in a format that's easier for humans to parse.
          Here's an example:

              $ cat /proc/$$/status
              Name:   bash
              Umask:  0022
              State:  S (sleeping)
              Tgid:   17248
              Ngid:   0
              Pid:    17248
              PPid:   17200
              TracerPid:      0
              Uid:    1000    1000    1000    1000
              Gid:    100     100     100     100
              FDSize: 256
              Groups: 16 33 100
              NStgid: 17248
              NSpid:  17248
              NSpgid: 17248
              NSsid:  17200
              VmPeak:     131168 kB
              VmSize:     131168 kB
              VmLck:           0 kB
              VmPin:           0 kB
              VmHWM:       13484 kB
              VmRSS:       13484 kB
              RssAnon:     10264 kB
              RssFile:      3220 kB
              RssShmem:        0 kB
              VmData:      10332 kB
              VmStk:         136 kB
              VmExe:         992 kB
              VmLib:        2104 kB
              VmPTE:          76 kB
              VmPMD:          12 kB
              VmSwap:          0 kB
              HugetlbPages:          0 kB        # 4.4
              Threads:        1
              SigQ:   0/3067
              SigPnd: 0000000000000000
              ShdPnd: 0000000000000000
              SigBlk: 0000000000010000
              SigIgn: 0000000000384004
              SigCgt: 000000004b813efb
              CapInh: 0000000000000000
              CapPrm: 0000000000000000
              CapEff: 0000000000000000
              CapBnd: ffffffffffffffff
              CapAmb:   0000000000000000
              Seccomp:        0
              Cpus_allowed:   00000001
              Cpus_allowed_list:      0
              Mems_allowed:   1
              Mems_allowed_list:      0
              voluntary_ctxt_switches:        150
              nonvoluntary_ctxt_switches:     545

          The fields are as follows:

          * Name: Command run by this process.

          * Umask: Process umask, expressed in octal with a leading  zero;
            see umask(2).  (Since Linux 4.7.)

          * State: Current state of the process.  One of "R (running)", "S
            (sleeping)", "D (disk  sleep)",  "T  (stopped)",  "T  (tracing
            stop)", "Z (zombie)", or "X (dead)".

          * Tgid: Thread group ID (i.e., Process ID).

          * Ngid: NUMA group ID (0 if none; since Linux 3.13).

          * Pid: Thread ID (see gettid(2)).

          * PPid: PID of parent process.

          * TracerPid: PID of process tracing this process (0 if not being
            traced).

          * Uid, Gid: Real, effective,  saved  set,  and  filesystem  UIDs
            (GIDs).

          * FDSize: Number of file descriptor slots currently allocated.

          * Groups: Supplementary group list.

          * NStgid  :  Thread  group  ID  (i.e.,  PID)  in each of the PID
            namespaces of which [pid] is a  member.   The  leftmost  entry
            shows  the  value  with  respect  to  the PID namespace of the
            reading process, followed by the value in successively  nested
            inner namespaces.  (Since Linux 4.1.)

          * NSpid:  Thread ID in each of the PID namespaces of which [pid]
            is a member.  The fields are ordered as  for  NStgid.   (Since
            Linux 4.1.)

          * NSpgid:  Process  group  ID  in  each of the PID namespaces of
            which [pid] is a  member.   The  fields  are  ordered  as  for
            NStgid.  (Since Linux 4.1.)

          * NSsid: descendant namespace session ID hierarchy Session ID in
            each of the PID namespaces of which [pid] is  a  member.   The
            fields are ordered as for NStgid.  (Since Linux 4.1.)

          * VmPeak: Peak virtual memory size.

          * VmSize: Virtual memory size.

          * VmLck: Locked memory size (see mlock(3)).

          * VmPin:  Pinned memory size (since Linux 3.2).  These are pages
            that can't be moved because something needs to directly access
            physical memory.

          * VmHWM: Peak resident set size ("high water mark").

          * VmRSS: Resident set size.  Note that the value here is the sum
            of RssAnon, RssFile, and RssShmem.

          * RssAnon: Size of  resident  anonymous  memory.   (since  Linux
            4.5).

          * RssFile: Size of resident file mappings.  (since Linux 4.5).

          * RssShmem:  Size  of  resident shared memory (includes System V
            shared memory, mappings from tmpfs(5),  and  shared  anonymous
            mappings).  (since Linux 4.5).

          * VmData, VmStk, VmExe: Size of data, stack, and text segments.

          * VmLib: Shared library code size.

          * VmPTE: Page table entries size (since Linux 2.6.10).

          * VmPMD: Size of second-level page tables (since Linux 4.0).

          * VmSwap:  Swapped-out  virtual memory size by anonymous private
            pages; shmem swap usage is not included (since Linux 2.6.34).

          * HugetlbPages: Size of hugetlb memory portions.   (since  Linux
            4.4).

          * Threads: Number of threads in process containing this thread.

          * SigQ:  This  field  contains  two slash-separated numbers that
            relate to queued signals for the real user ID of this process.
            The  first  of these is the number of currently queued signals
            for this real user ID, and the second is the resource limit on
            the  number  of  queued  signals  for  this  process  (see the
            description of RLIMIT_SIGPENDING in getrlimit(2)).

          * SigPnd, ShdPnd: Number of signals pending for thread  and  for
            process as a whole (see pthreads(7) and signal(7)).

          * SigBlk,   SigIgn,   SigCgt:  Masks  indicating  signals  being
            blocked, ignored, and caught (see signal(7)).

          * CapInh, CapPrm,  CapEff:  Masks  of  capabilities  enabled  in
            inheritable,    permitted,    and    effective    sets    (see
            capabilities(7)).

          * CapBnd: Capability  Bounding  set  (since  Linux  2.6.26,  see
            capabilities(7)).

          * CapAmb:   Ambient   capability   set  (since  Linux  4.3,  see
            capabilities(7)).

          * Seccomp: Seccomp mode of the process  (since  Linux  3.8,  see
            seccomp(2)).    0   means   SECCOMP_MODE_DISABLED;   1   means
            SECCOMP_MODE_STRICT; 2 means SECCOMP_MODE_FILTER.  This  field
            is   provided   only   if   the  kernel  was  built  with  the
            CONFIG_SECCOMP kernel configuration option enabled.

          * Cpus_allowed: Mask of CPUs  on  which  this  process  may  run
            (since Linux 2.6.24, see cpuset(7)).

          * Cpus_allowed_list:  Same  as  previous,  but  in "list format"
            (since Linux 2.6.26, see cpuset(7)).

          * Mems_allowed: Mask of memory nodes  allowed  to  this  process
            (since Linux 2.6.24, see cpuset(7)).

          * Mems_allowed_list:  Same  as  previous,  but  in "list format"
            (since Linux 2.6.26, see cpuset(7)).

          * voluntary_ctxt_switches, nonvoluntary_ctxt_switches: Number of
            voluntary   and  involuntary  context  switches  (since  Linux
            2.6.23).

   /proc/[pid]/syscall (since Linux 2.6.27)
          This file exposes the system call number and argument  registers
          for  the  system  call  currently being executed by the process,
          followed by the values of the stack pointer and program  counter
          registers.   The  values  of  all  six  argument  registers  are
          exposed, although most system calls use fewer registers.

          If the process is blocked, but not in a system  call,  then  the
          file displays -1 in place of the system call number, followed by
          just the values of the stack pointer and  program  counter.   If
          process  is  not blocked, then the file contains just the string
          "running".

          This file is present only if  the  kernel  was  configured  with
          CONFIG_HAVE_ARCH_TRACEHOOK.

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

   /proc/[pid]/task (since Linux 2.6.0-test6)
          This is a directory that  contains  one  subdirectory  for  each
          thread  in  the  process.   The name of each subdirectory is the
          numerical thread ID  ([tid])  of  the  thread  (see  gettid(2)).
          Within  each  of  these  subdirectories, there is a set of files
          with the same  names  and  contents  as  under  the  /proc/[pid]
          directories.  For attributes that are shared by all threads, the
          contents  for  each  of   the   files   under   the   task/[tid]
          subdirectories  will be the same as in the corresponding file in
          the parent  /proc/[pid]  directory  (e.g.,  in  a  multithreaded
          process,  all  of  the  task/[tid]/cwd  files will have the same
          value as the /proc/[pid]/cwd file in the parent directory, since
          all of the threads in a process share a working directory).  For
          attributes that are distinct for each thread, the  corresponding
          files  under task/[tid] may have different values (e.g., various
          fields in each of the task/[tid]/status files may  be  different
          for each thread), or they might not exist in /proc/[pid] at all.
          In a multithreaded process, the contents of the /proc/[pid]/task
          directory  are  not  available  if  the  main thread has already
          terminated (typically by calling pthread_exit(3)).

   /proc/[pid]/task/[tid]/children (since Linux 3.5)
          A space-separated list of child tasks of this task.  Each  child
          task is represented by its TID.

          This option is intended for use by the checkpoint-restore (CRIU)
          system, and reliably provides a list of children only if all  of
          the  child  processes  are  stopped or frozen.  It does not work
          properly if children of the target task exit while the  file  is
          being  read!  Exiting children may cause non-exiting children to
          be omitted from the list.  This makes this interface  even  more
          unreliable  than  classic  PID-based approaches if the inspected
          task and its  children  aren't  frozen,  and  most  code  should
          probably not use this interface.

          Until  Linux  4.2, the presence of this file was governed by the
          CONFIG_CHECKPOINT_RESTORE kernel  configuration  option.   Since
          Linux 4.2, it is governed by the CONFIG_PROC_CHILDREN option.

   /proc/[pid]/timers (since Linux 3.10)
          A  list  of  the  POSIX  timers for this process.  Each timer is
          listed with a line that  starts  with  the  string  "ID:".   For
          example:

              ID: 1
              signal: 60/00007fff86e452a8
              notify: signal/pid.2634
              ClockID: 0
              ID: 0
              signal: 60/00007fff86e452a8
              notify: signal/pid.2634
              ClockID: 1

          The lines shown for each timer have the following meanings:

          ID     The ID for this timer.  This is not the same as the timer
                 ID returned by timer_create(2); rather, it  is  the  same
                 kernel-internal  ID  that is available via the si_timerid
                 field of the siginfo_t structure (see sigaction(2)).

          signal This is the signal number that this timer uses to deliver
                 notifications   followed   by   a  slash,  and  then  the
                 sigev_value value supplied to the signal handler.   Valid
                 only for timers that notify via a signal.

          notify The  part  before  the slash specifies the mechanism that
                 this timer uses to deliver notifications, and is  one  of
                 "thread", "signal", or "none".  Immediately following the
                 slash  is  either  the  string  "tid"  for  timers   with
                 SIGEV_THREAD_ID  notification,  or  "pid" for timers that
                 notify by other mechanisms.  Following the "." is the PID
                 of  the  process  (or the kernel thread ID of the thread)
                 that will be delivered a signal  if  the  timer  delivers
                 notifications via a signal.

          ClockID
                 This  field  identifies the clock that the timer uses for
                 measuring time.  For most clocks, this is a  number  that
                 matches  one  of the user-space CLOCK_* constants exposed
                 via <time.h>.   CLOCK_PROCESS_CPUTIME_ID  timers  display
                 with     a     value     of    -6    in    this    field.
                 CLOCK_THREAD_CPUTIME_ID timers display with a value of -2
                 in this field.

          This  file is available only when the kernel was configured with
          CONFIG_CHECKPOINT_RESTORE.

   /proc/[pid]/timerslack_ns (since Linux 4.6)
          This file exposes the process's  "current"  timer  slack  value,
          expressed  in  nanoseconds.   The file is writable, allowing the
          process's timer slack value to be changed.  Writing  0  to  this
          file  resets  the  "current"  timer slack to the "default" timer
          slack  value.   For  further  details,  see  the  discussion  of
          PR_SET_TIMERSLACK in prctl(2).

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

   /proc/[pid]/uid_map, /proc/[pid]/gid_map (since Linux 3.5)
          See user_namespaces(7).

   /proc/[pid]/wchan (since Linux 2.6.0)
          The symbolic name corresponding to the location  in  the  kernel
          where the process is sleeping.

          Permission  to  access  this file is governed by a ptrace access
          mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

   /proc/apm
          Advanced power management version and battery  information  when
          CONFIG_APM is defined at kernel compilation time.

   /proc/buddyinfo
          This  file  contains  information  which  is used for diagnosing
          memory  fragmentation  issues.   Each  line  starts   with   the
          identification  of  the  node  and  the  name  of the zone which
          together identify a memory region This is then followed  by  the
          count  of  available  chunks  of  a certain order in which these
          zones are split.  The size in bytes of a certain order is  given
          by the formula:

              (2^order) * PAGE_SIZE

          The  binary  buddy  allocator  algorithm  inside the kernel will
          split one chunk into two chunks of a smaller  order  (thus  with
          half  the size) or combine two contiguous chunks into one larger
          chunk of a higher order (thus with double the size)  to  satisfy
          allocation  requests  and  to counter memory fragmentation.  The
          order matches the column number, when starting to count at zero.

          For example on a x86_64 system:

  Node 0, zone     DMA     1    1    1    0    2    1    1    0    1    1    3
  Node 0, zone   DMA32    65   47    4   81   52   28   13   10    5    1  404
  Node 0, zone  Normal   216   55  189  101   84   38   37   27    5    3  587

          In this example, there is one node containing  three  zones  and
          there  are  11  different  chunk  sizes.   If the page size is 4
          kilobytes, then the first zone called DMA (on x86 the  first  16
          megabyte  of  memory)  has  1  chunk  of  4  kilobytes (order 0)
          available and has 3 chunks of 4 megabytes (order 10) available.

          If the memory is heavily fragmented,  the  counters  for  higher
          order  chunks  will  be  zero and allocation of large contiguous
          areas will fail.

          Further  information  about  the   zones   can   be   found   in
          /proc/zoneinfo.

   /proc/bus
          Contains subdirectories for installed busses.

   /proc/bus/pccard
          Subdirectory  for  PCMCIA  devices  when CONFIG_PCMCIA is set at
          kernel compilation time.

   /proc/bus/pccard/drivers

   /proc/bus/pci
          Contains various bus subdirectories and pseudo-files  containing
          information  about  PCI  busses,  installed  devices, and device
          drivers.  Some of these files are not ASCII.

   /proc/bus/pci/devices
          Information about PCI devices.  They  may  be  accessed  through
          lspci(8) and setpci(8).

   /proc/cgroups (since Linux 2.6.24)
          See cgroups(7).

   /proc/cmdline
          Arguments  passed  to the Linux kernel at boot time.  Often done
          via a boot manager such as lilo(8) or grub(8).

   /proc/config.gz (since Linux 2.6)
          This file exposes the configuration options that  were  used  to
          build  the  currently running kernel, in the same format as they
          would  be  shown  in  the  .config  file  that   resulted   when
          configuring  the  kernel  (using  make  xconfig, make config, or
          similar).  The file contents are compressed; view or search them
          using  zcat(1)  and  zgrep(1).   As long as no changes have been
          made to the following file, the contents of /proc/config.gz  are
          the same as those provided by :

              cat /lib/modules/$(uname -r)/build/.config

          /proc/config.gz  is  provided  only  if the kernel is configured
          with CONFIG_IKCONFIG_PROC.

   /proc/crypto
          A list of the ciphers provided by the kernel  crypto  API.   For
          details,  see  the  kernel Linux Kernel Crypto API documentation
          available     under     the     kernel     source      directory
          Documentation/DocBook.  (That documentation can be built using a
          command such as make htmldocs  in  the  root  directory  of  the
          kernel source tree.)

   /proc/cpuinfo
          This  is  a  collection of CPU and system architecture dependent
          items, for each supported architecture a  different  list.   Two
          common   entries  are  processor  which  gives  CPU  number  and
          bogomips; a system constant that  is  calculated  during  kernel
          initialization.   SMP  machines  have  information for each CPU.
          The lscpu(1) command gathers its information from this file.

   /proc/devices
          Text listing of major numbers and device groups.   This  can  be
          used by MAKEDEV scripts for consistency with the kernel.

   /proc/diskstats (since Linux 2.5.69)
          This  file  contains  disk  I/O statistics for each disk device.
          See the Linux kernel source file  Documentation/iostats.txt  for
          further information.

   /proc/dma
          This  is a list of the registered ISA DMA (direct memory access)
          channels in use.

   /proc/driver
          Empty subdirectory.

   /proc/execdomains
          List of the execution domains (ABI personalities).

   /proc/fb
          Frame buffer information when CONFIG_FB is defined during kernel
          compilation.

   /proc/filesystems
          A  text  listing  of  the filesystems which are supported by the
          kernel, namely filesystems which were compiled into  the  kernel
          or  whose  kernel  modules  are  currently  loaded.   (See  also
          filesystems(5).)  If a filesystem is marked with  "nodev",  this
          means  that  it  does  not  require a block device to be mounted
          (e.g., virtual filesystem, network filesystem).

          Incidentally,  this  file  may  be  used  by  mount(8)  when  no
          filesystem  is  specified  and it didn't manage to determine the
          filesystem type.  Then filesystems contained in  this  file  are
          tried (excepted those that are marked with "nodev").

   /proc/fs
          Contains   subdirectories   that  in  turn  contain  files  with
          information about (certain) mounted filesystems.

   /proc/ide
          This directory exists on systems with the IDE  bus.   There  are
          directories  for  each  IDE  channel and attached device.  Files
          include:

              cache              buffer size in KB
              capacity           number of sectors
              driver             driver version
              geometry           physical and logical geometry
              identify           in hexadecimal
              media              media type
              model              manufacturer's model number
              settings           drive settings
              smart_thresholds   in hexadecimal
              smart_values       in hexadecimal

          The hdparm(8) utility provides access to this information  in  a
          friendly format.

   /proc/interrupts
          This  is  used to record the number of interrupts per CPU per IO
          device.   Since  Linux  2.6.24,  for   the   i386   and   x86_64
          architectures,  at least, this also includes interrupts internal
          to the system (that is, not associated with a device  as  such),
          such   as   NMI   (nonmaskable   interrupt),  LOC  (local  timer
          interrupt), and for SMP systems, TLB (TLB flush interrupt),  RES
          (rescheduling  interrupt), CAL (remote function call interrupt),
          and possibly others.  Very easy  to  read  formatting,  done  in
          ASCII.

   /proc/iomem
          I/O memory map in Linux 2.4.

   /proc/ioports
          This is a list of currently registered Input-Output port regions
          that are in use.

   /proc/kallsyms (since Linux 2.5.71)
          This holds the kernel exported symbol definitions  used  by  the
          modules(X)  tools to dynamically link and bind loadable modules.
          In Linux 2.5.47  and  earlier,  a  similar  file  with  slightly
          different syntax was named ksyms.

   /proc/kcore
          This  file  represents  the physical memory of the system and is
          stored in the ELF core file format.  With this pseudo-file,  and
          an unstripped kernel (/usr/src/linux/vmlinux) binary, GDB can be
          used to examine the current state of any kernel data structures.

          The total length of the file is  the  size  of  physical  memory
          (RAM) plus 4KB.

   /proc/kmsg
          This  file  can  be used instead of the syslog(2) system call to
          read kernel messages.  A process must have superuser  privileges
          to  read  this file, and only one process should read this file.
          This file should not be read if  a  syslog  process  is  running
          which  uses  the  syslog(2)  system  call facility to log kernel
          messages.

          Information in this file is retrieved with the dmesg(1) program.

   /proc/kpagecount (since Linux 2.6.25)
          This file contains a 64-bit count of the number  of  times  each
          physical page frame is mapped, indexed by page frame number (see
          the discussion of /proc/[pid]/pagemap).

          The   /proc/kpagecount   file   is   present   only    if    the
          CONFIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

   /proc/kpageflags (since Linux 2.6.25)
          This  file  contains 64-bit masks corresponding to each physical
          page frame;  it  is  indexed  by  page  frame  number  (see  the
          discussion of /proc/[pid]/pagemap).  The bits are as follows:

               0 - KPF_LOCKED
               1 - KPF_ERROR
               2 - KPF_REFERENCED
               3 - KPF_UPTODATE
               4 - KPF_DIRTY
               5 - KPF_LRU
               6 - KPF_ACTIVE
               7 - KPF_SLAB
               8 - KPF_WRITEBACK
               9 - KPF_RECLAIM
              10 - KPF_BUDDY
              11 - KPF_MMAP           (since Linux 2.6.31)
              12 - KPF_ANON           (since Linux 2.6.31)
              13 - KPF_SWAPCACHE      (since Linux 2.6.31)
              14 - KPF_SWAPBACKED     (since Linux 2.6.31)
              15 - KPF_COMPOUND_HEAD  (since Linux 2.6.31)
              16 - KPF_COMPOUND_TAIL  (since Linux 2.6.31)
              16 - KPF_HUGE           (since Linux 2.6.31)
              18 - KPF_UNEVICTABLE    (since Linux 2.6.31)
              19 - KPF_HWPOISON       (since Linux 2.6.31)
              20 - KPF_NOPAGE         (since Linux 2.6.31)
              21 - KPF_KSM            (since Linux 2.6.32)
              22 - KPF_THP            (since Linux 3.4)

          For  further  details  on  the  meanings  of these bits, see the
          kernel source file Documentation/vm/pagemap.txt.  Before  kernel
          2.6.29,  KPF_WRITEBACK,  KPF_RECLAIM,  KPF_BUDDY, and KPF_LOCKED
          did not report correctly.

          The   /proc/kpageflags   file   is   present   only    if    the
          CONFIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

   /proc/ksyms (Linux 1.1.23-2.5.47)
          See /proc/kallsyms.

   /proc/loadavg
          The  first  three  fields  in this file are load average figures
          giving the number of jobs in the run queue (state R) or  waiting
          for disk I/O (state D) averaged over 1, 5, and 15 minutes.  They
          are the same as the load average numbers given by uptime(1)  and
          other  programs.   The  fourth  field  consists  of  two numbers
          separated by a slash (/).  The first of these is the  number  of
          currently   runnable   kernel  scheduling  entities  (processes,
          threads).  The value after the slash is  the  number  of  kernel
          scheduling  entities  that  currently  exist on the system.  The
          fifth field is the PID of the process  that  was  most  recently
          created on the system.

   /proc/locks
          This  file  shows current file locks (flock(2) and fcntl(2)) and
          leases (fcntl(2)).  The lslocks(8) command provides a  bit  more
          information about each lock.

   /proc/malloc (only up to and including Linux 2.2)
          This  file  is  present  only if CONFIG_DEBUG_MALLOC was defined
          during compilation.

   /proc/meminfo
          This file reports statistics about memory usage on  the  system.
          It  is  used  by  free(1)  to report the amount of free and used
          memory (both physical and swap) on the system  as  well  as  the
          shared  memory and buffers used by the kernel.  Each line of the
          file consists of a parameter name,  followed  by  a  colon,  the
          value of the parameter, and an option unit of measurement (e.g.,
          "kB").  The list below describes the  parameter  names  and  the
          format  specifier  required  to read the field value.  Except as
          noted below, all of the fields have been present since at  least
          Linux  2.6.0.   Some fields are displayed only if the kernel was
          configured with various options; those dependencies are noted in
          the list.

          MemTotal %lu
                 Total usable RAM (i.e., physical RAM minus a few reserved
                 bits and the kernel binary code).

          MemFree %lu
                 The sum of LowFree+HighFree.

          MemAvailable %lu (since Linux 3.14)
                 An estimate of how much memory is available for  starting
                 new applications, without swapping.

          Buffers %lu
                 Relatively  temporary  storage  for  raw disk blocks that
                 shouldn't get tremendously large (20MB or so).

          Cached %lu
                 In-memory cache for files read from the  disk  (the  page
                 cache).  Doesn't include SwapCached.

          SwapCached %lu
                 Memory  that once was swapped out, is swapped back in but
                 still also is in the swap file.  (If memory  pressure  is
                 high,  these  pages  don't  need  to be swapped out again
                 because they are already in the swap  file.   This  saves
                 I/O.)

          Active %lu
                 Memory  that  has been used more recently and usually not
                 reclaimed unless absolutely necessary.

          Inactive %lu
                 Memory which has been less recently  used.   It  is  more
                 eligible to be reclaimed for other purposes.

          Active(anon) %lu (since Linux 2.6.28)
                 [To be documented.]

          Inactive(anon) %lu (since Linux 2.6.28)
                 [To be documented.]

          Active(file) %lu (since Linux 2.6.28)
                 [To be documented.]

          Inactive(file) %lu (since Linux 2.6.28)
                 [To be documented.]

          Unevictable %lu (since Linux 2.6.28)
                 (From  Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU was
                 required.)  [To be documented.]

          Mlocked %lu (since Linux 2.6.28)
                 (From Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU  was
                 required.)  [To be documented.]

          HighTotal %lu
                 (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                 Total amount of highmem.  Highmem  is  all  memory  above
                 ~860MB  of physical memory.  Highmem areas are for use by
                 user-space programs, or for the page cache.   The  kernel
                 must  use  tricks to access this memory, making it slower
                 to access than lowmem.

          HighFree %lu
                 (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                 Amount of free highmem.

          LowTotal %lu
                 (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                 Total amount of lowmem.  Lowmem is memory  which  can  be
                 used  for everything that highmem can be used for, but it
                 is also available for the kernel's use for its  own  data
                 structures.    Among  many  other  things,  it  is  where
                 everything from Slab is  allocated.   Bad  things  happen
                 when you're out of lowmem.

          LowFree %lu
                 (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                 Amount of free lowmem.

          MmapCopy %lu (since Linux 2.6.29)
                 (CONFIG_MMU is required.)  [To be documented.]

          SwapTotal %lu
                 Total amount of swap space available.

          SwapFree %lu
                 Amount of swap space that is currently unused.

          Dirty %lu
                 Memory which is waiting to get written back to the disk.

          Writeback %lu
                 Memory which is actively being written back to the disk.

          AnonPages %lu (since Linux 2.6.18)
                 Non-file backed pages mapped into user-space page tables.

          Mapped %lu
                 Files which have been mapped into memory (with  mmap(2)),
                 such as libraries.

          Shmem %lu (since Linux 2.6.32)
                 Amount of memory consumed in tmpfs(5) filesystems.

          Slab %lu
                 In-kernel data structures cache.

          SReclaimable %lu (since Linux 2.6.19)
                 Part of Slab, that might be reclaimed, such as caches.

          SUnreclaim %lu (since Linux 2.6.19)
                 Part   of  Slab,  that  cannot  be  reclaimed  on  memory
                 pressure.

          KernelStack %lu (since Linux 2.6.32)
                 Amount of memory allocated to kernel stacks.

          PageTables %lu (since Linux 2.6.18)
                 Amount of memory dedicated to the lowest  level  of  page
                 tables.

          Quicklists %lu (since Linux 2.6.27)
                 (CONFIG_QUICKLIST is required.)  [To be documented.]

          NFS_Unstable %lu (since Linux 2.6.18)
                 NFS  pages  sent  to the server, but not yet committed to
                 stable storage.

          Bounce %lu (since Linux 2.6.18)
                 Memory used for block device "bounce buffers".

          WritebackTmp %lu (since Linux 2.6.26)
                 Memory used by FUSE for temporary writeback buffers.

          CommitLimit %lu (since Linux 2.6.10)
                 This is the total amount of memory currently available to
                 be allocated on the system, expressed in kilobytes.  This
                 limit is adhered to only if strict overcommit  accounting
                 is  enabled  (mode  2 in /proc/sys/vm/overcommit_memory).
                 The  limit  is  calculated  according  to   the   formula
                 described   under   /proc/sys/vm/overcommit_memory.   For
                 further   details,   see   the   kernel    source    file
                 Documentation/vm/overcommit-accounting.

          Committed_AS %lu
                 The  amount  of memory presently allocated on the system.
                 The committed memory is a sum of all of the memory  which
                 has  been allocated by processes, even if it has not been
                 "used" by them as of yet.  A process which allocates  1GB
                 of  memory (using malloc(3) or similar), but touches only
                 300MB of that memory will show up as using only 300MB  of
                 memory even if it has the address space allocated for the
                 entire 1GB.

                 This 1GB is memory which has been "committed" to  by  the
                 VM  and  can  be  used  at  any  time  by  the allocating
                 application.   With  strict  overcommit  enabled  on  the
                 system   (mode   2   in  /proc/sys/vm/overcommit_memory),
                 allocations which would exceed the CommitLimit  will  not
                 be  permitted.   This is useful if one needs to guarantee
                 that processes will not fail due to lack of  memory  once
                 that memory has been successfully allocated.

          VmallocTotal %lu
                 Total size of vmalloc memory area.

          VmallocUsed %lu
                 Amount of vmalloc area which is used.

          VmallocChunk %lu
                 Largest contiguous block of vmalloc area which is free.

          HardwareCorrupted %lu (since Linux 2.6.32)
                 (CONFIG_MEMORY_FAILURE is required.)  [To be documented.]

          AnonHugePages %lu (since Linux 2.6.38)
                 (CONFIG_TRANSPARENT_HUGEPAGE   is   required.)   Non-file
                 backed huge pages mapped into user-space page tables.

          ShmemHugePages %lu (since Linux 4.8)
                 (CONFIG_TRANSPARENT_HUGEPAGE is required.)   Memory  used
                 by shared memory (shmem) and tmpfs(5) allocated with huge
                 pages

          ShmemPmdMapped %lu (since Linux 4.8)
                 (CONFIG_TRANSPARENT_HUGEPAGE is required.)  Shared memory
                 mapped into user space with huge pages.

          CmaTotal %lu (since Linux 3.1)
                 Total    CMA   (Contiguous   Memory   Allocator)   pages.
                 (CONFIG_CMA is required.)

          CmaFree %lu (since Linux 3.1)
                 Free   CMA   (Contiguous   Memory    Allocator)    pages.
                 (CONFIG_CMA is required.)

          HugePages_Total %lu
                 (CONFIG_HUGETLB_PAGE  is required.)  The size of the pool
                 of huge pages.

          HugePages_Free %lu
                 (CONFIG_HUGETLB_PAGE is required.)  The  number  of  huge
                 pages in the pool that are not yet allocated.

          HugePages_Rsvd %lu (since Linux 2.6.17)
                 (CONFIG_HUGETLB_PAGE is required.)  This is the number of
                 huge pages for which a commitment to  allocate  from  the
                 pool  has been made, but no allocation has yet been made.
                 These reserved huge pages guarantee that  an  application
                 will  be  able  to  allocate a huge page from the pool of
                 huge pages at fault time.

          HugePages_Surp %lu (since Linux 2.6.24)
                 (CONFIG_HUGETLB_PAGE is required.)  This is the number of
                 huge   pages   in   the   pool   above   the   value   in
                 /proc/sys/vm/nr_hugepages.  The maximum number of surplus
                 huge         pages         is        controlled        by
                 /proc/sys/vm/nr_overcommit_hugepages.

          Hugepagesize %lu
                 (CONFIG_HUGETLB_PAGE is  required.)   The  size  of  huge
                 pages.

          DirectMap4k %lu (since Linux 2.6.27)
                 Number  of  bytes of RAM linearly mapped by kernel in 4kB
                 pages.  (x86.)

          DirectMap4M %lu (since Linux 2.6.27)
                 Number of bytes of RAM linearly mapped by kernel  in  4MB
                 pages.    (x86   with   CONFIG_X86_64  or  CONFIG_X86_PAE
                 enabled.)

          DirectMap2M %lu (since Linux 2.6.27)
                 Number of bytes of RAM linearly mapped by kernel  in  2MB
                 pages.     (x86    with    neither    CONFIG_X86_64   nor
                 CONFIG_X86_PAE enabled.)

          DirectMap1G %lu (since Linux 2.6.27)
                 (x86  with  CONFIG_X86_64  and  CONFIG_X86_DIRECT_GBPAGES
                 enabled.)

   /proc/modules
          A  text list of the modules that have been loaded by the system.
          See also lsmod(8).

   /proc/mounts
          Before  kernel  2.4.19,  this  file  was  a  list  of  all   the
          filesystems   currently   mounted   on  the  system.   With  the
          introduction of per-process mount  namespaces  in  Linux  2.4.19
          (see   mount_namespaces(7)),   this   file   became  a  link  to
          /proc/self/mounts, which lists the mount points of the process's
          own  mount  namespace.  The format of this file is documented in
          fstab(5).

   /proc/mtrr
          Memory Type Range Registers.  See the Linux kernel  source  file
          Documentation/mtrr.txt for details.

   /proc/net
          This   directory   contains  various  files  and  subdirectories
          containing information about the networking  layer.   The  files
          contain  ASCII  structures  and  are,  therefore,  readable with
          cat(1).  However, the standard netstat(8)  suite  provides  much
          cleaner access to these files.

          With  the  advent  of  network  namespaces,  various information
          relating   to   the   network   stack   is   virtualized    (see
          namespaces(7)).   Thus,  since  Linux  2.6.25,  /proc/net  is  a
          symbolic link to the directory  /proc/self/net,  which  contains
          the  same files and directories as listed below.  However, these
          files and directories now expose  information  for  the  network
          namespace of which the process is a member.

   /proc/net/arp
          This  holds  an ASCII readable dump of the kernel ARP table used
          for address resolutions.  It will show both dynamically  learned
          and preprogrammed ARP entries.  The format is:

    IP address     HW type   Flags     HW address          Mask   Device
    192.168.0.50   0x1       0x2       00:50:BF:25:68:F3   *      eth0
    192.168.0.250  0x1       0xc       00:00:00:00:00:00   *      eth0

          Here "IP address" is the IPv4 address of the machine and the "HW
          type" is the hardware type of the  address  from  RFC 826.   The
          flags are the internal flags of the ARP structure (as defined in
          /usr/include/linux/if_arp.h) and the "HW address"  is  the  data
          link layer mapping for that IP address if it is known.

   /proc/net/dev
          The  dev pseudo-file contains network device status information.
          This gives the number of received and sent packets,  the  number
          of  errors and collisions and other basic statistics.  These are
          used by the ifconfig(8) program to report  device  status.   The
          format is:

 Inter-|   Receive                                                |  Transmit
  face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
     lo: 2776770   11307    0    0    0     0          0         0  2776770   11307    0    0    0     0       0          0
   eth0: 1215645    2751    0    0    0     0          0         0  1782404    4324    0    0    0   427       0          0
   ppp0: 1622270    5552    1    0    0     0          0         0   354130    5669    0    0    0     0       0          0
   tap0:    7714      81    0    0    0     0          0         0     7714      81    0    0    0     0       0          0

   /proc/net/dev_mcast
          Defined in /usr/src/linux/net/core/dev_mcast.c:
               indx interface_name  dmi_u dmi_g dmi_address
               2    eth0            1     0     01005e000001
               3    eth1            1     0     01005e000001
               4    eth2            1     0     01005e000001

   /proc/net/igmp
          Internet     Group     Management    Protocol.     Defined    in
          /usr/src/linux/net/core/igmp.c.

   /proc/net/rarp
          This file uses the same format as the arp file and contains  the
          current reverse mapping database used to provide rarp(8) reverse
          address lookup services.  If RARP is  not  configured  into  the
          kernel, this file will not be present.

   /proc/net/raw
          Holds  a  dump of the RAW socket table.  Much of the information
          is not of use apart from  debugging.   The  "sl"  value  is  the
          kernel  hash  slot  for  the  socket, the "local_address" is the
          local address and protocol number pair.  "St"  is  the  internal
          status  of  the  socket.   The "tx_queue" and "rx_queue" are the
          outgoing and incoming data  queue  in  terms  of  kernel  memory
          usage.   The "tr", "tm->when", and "rexmits" fields are not used
          by RAW.  The "uid" field holds the effective UID of the  creator
          of the socket.

   /proc/net/snmp
          This file holds the ASCII data needed for the IP, ICMP, TCP, and
          UDP management information bases for an SNMP agent.

   /proc/net/tcp
          Holds a dump of the TCP socket table.  Much of  the  information
          is  not  of  use  apart  from  debugging.  The "sl" value is the
          kernel hash slot for the  socket,  the  "local_address"  is  the
          local  address  and  port number pair.  The "rem_address" is the
          remote address and port number pair (if connected).  "St" is the
          internal  status  of  the socket.  The "tx_queue" and "rx_queue"
          are the outgoing and incoming data  queue  in  terms  of  kernel
          memory  usage.   The "tr", "tm->when", and "rexmits" fields hold
          internal information of the kernel socket state and  are  useful
          only  for debugging.  The "uid" field holds the effective UID of
          the creator of the socket.

   /proc/net/udp
          Holds a dump of the UDP socket table.  Much of  the  information
          is  not  of  use  apart  from  debugging.  The "sl" value is the
          kernel hash slot for the  socket,  the  "local_address"  is  the
          local  address  and  port number pair.  The "rem_address" is the
          remote address and port number pair (if connected).  "St" is the
          internal  status  of  the socket.  The "tx_queue" and "rx_queue"
          are the outgoing and incoming data  queue  in  terms  of  kernel
          memory  usage.   The  "tr", "tm->when", and "rexmits" fields are
          not used by UDP.  The "uid" field holds the effective UID of the
          creator of the socket.  The format is:

 sl  local_address rem_address   st tx_queue rx_queue tr rexmits  tm->when uid
  1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
  1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
  1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0

   /proc/net/unix
          Lists  the  UNIX  domain  sockets  present within the system and
          their status.  The format is:
          Num RefCount Protocol Flags    Type St Path
           0: 00000002 00000000 00000000 0001 03
           1: 00000001 00000000 00010000 0001 01 /dev/printer

          The fields are as follows:

          Num:      the kernel table slot number.

          RefCount: the number of users of the socket.

          Protocol: currently always 0.

          Flags:    the internal kernel flags holding the  status  of  the
                    socket.

          Type:     the  socket  type.   For  SOCK_STREAM sockets, this is
                    0001; for SOCK_DGRAM sockets,  it  is  0002;  and  for
                    SOCK_SEQPACKET sockets, it is 0005.

          St:       the internal state of the socket.

          Path:     the bound path (if any) of the socket.  Sockets in the
                    abstract namespace are included in the list,  and  are
                    shown  with  a  Path that commences with the character
                    '@'.

   /proc/net/netfilter/nfnetlink_queue
          This  file  contains  information  about  netfilter   user-space
          queueing,  if  used.  Each line represents a queue.  Queues that
          have not been subscribed to by user space are not shown.

             1   4207     0  2 65535     0     0        0  1
            (1)   (2)    (3)(4)  (5)    (6)   (7)      (8)

          The fields in each line are:

          (1)  The ID of the queue.  This matches what is specified in the
               --queue-num  or  --queue-balance options to the iptables(8)
               NFQUEUE  target.   See  iptables-extensions(8)   for   more
               information.

          (2)  The netlink port ID subscribed to the queue.

          (3)  The  number  of  packets currently queued and waiting to be
               processed by the application.

          (4)  The copy mode of the queue.  It is either 1 (metadata only)
               or 2 (also copy payload data to user space).

          (5)  Copy  range;  that  is,  how  many  bytes of packet payload
               should be copied to user space at most.

          (6)  queue dropped.  Number of packets that had to be dropped by
               the kernel because too many packets are already waiting for
               user space to send back the mandatory accept/drop verdicts.

          (7)  queue user dropped.  Number of packets  that  were  dropped
               within  the  netlink  subsystem.  Such drops usually happen
               when the corresponding socket buffer is full; that is, user
               space is not able to read messages fast enough.

          (8)  sequence  number.  Every queued packet is associated with a
               (32-bit) monotonically-increasing  sequence  number.   This
               shows the ID of the most recent packet queued.

          The  last  number  exists  only for compatibility reasons and is
          always 1.

   /proc/partitions
          Contains the major and minor numbers of each partition  as  well
          as the number of 1024-byte blocks and the partition name.

   /proc/pci
          This  is  a  listing  of  all  PCI  devices  found during kernel
          initialization and their configuration.

          This file has been deprecated in favor of a new /proc  interface
          for  PCI  (/proc/bus/pci).   It  became  optional  in  Linux 2.2
          (available with CONFIG_PCI_OLD_PROC set at kernel  compilation).
          It  became  once more nonoptionally enabled in Linux 2.4.  Next,
          it  was  deprecated  in  Linux   2.6   (still   available   with
          CONFIG_PCI_LEGACY_PROC  set),  and  finally  removed  altogether
          since Linux 2.6.17.

   /proc/profile (since Linux 2.4)
          This file is present only if the  kernel  was  booted  with  the
          profile=1  command-line  option.   It  exposes  kernel profiling
          information in  a  binary  format  for  use  by  readprofile(1).
          Writing  (e.g.,  an  empty  string)  to  this  file  resets  the
          profiling counters; on  some  architectures,  writing  a  binary
          integer  "profiling  multiplier"  of  size  sizeof(int) sets the
          profiling interrupt frequency.

   /proc/scsi
          A directory with the scsi mid-level pseudo-file and various SCSI
          low-level driver directories, which contain a file for each SCSI
          host in this system, all of which give the status of  some  part
          of  the SCSI IO subsystem.  These files contain ASCII structures
          and are, therefore, readable with cat(1).

          You can also write to some  of  the  files  to  reconfigure  the
          subsystem or switch certain features on or off.

   /proc/scsi/scsi
          This  is a listing of all SCSI devices known to the kernel.  The
          listing  is  similar  to  the  one  seen  during  bootup.   scsi
          currently  supports  only  the  add-single-device  command which
          allows root to add a hotplugged device  to  the  list  of  known
          devices.

          The command

              echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi

          will  cause host scsi1 to scan on SCSI channel 0 for a device on
          ID 5 LUN 0.  If there is already a device known on this  address
          or the address is invalid, an error will be returned.

   /proc/scsi/[drivername]
          [drivername]  can  currently  be  NCR53c7xx,  aha152x,  aha1542,
          aha1740, aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000,
          pas16,  qlogic,  scsi_debug, seagate, t128, u15-24f, ultrastore,
          or wd7000.  These directories  show  up  for  all  drivers  that
          registered  at least one SCSI HBA.  Every directory contains one
          file per registered host.  Every host-file is  named  after  the
          number the host was assigned during initialization.

          Reading   these   files   will  usually  show  driver  and  host
          configuration, statistics, and so on.

          Writing to these files  allows  different  things  on  different
          hosts.   For  example,  with the latency and nolatency commands,
          root can switch on and off command latency measurement  code  in
          the  eata_dma driver.  With the lockup and unlock commands, root
          can control bus lockups simulated by the scsi_debug driver.

   /proc/self
          This  directory  refers  to  the  process  accessing  the  /proc
          filesystem, and is identical to the /proc directory named by the
          process ID of the same process.

   /proc/slabinfo
          Information about kernel caches.  Since Linux 2.6.16  this  file
          is  present  only if the CONFIG_SLAB kernel configuration option
          is enabled.  The columns in /proc/slabinfo are:

              cache-name
              num-active-objs
              total-objs
              object-size
              num-active-slabs
              total-slabs
              num-pages-per-slab

          See slabinfo(5) for details.

   /proc/stat
          kernel/system statistics.   Varies  with  architecture.   Common
          entries include:

          cpu  3357 0 4313 1362393
                 The   amount  of  time,  measured  in  units  of  USER_HZ
                 (1/100ths  of  a  second  on  most   architectures,   use
                 sysconf(_SC_CLK_TCK) to obtain the right value), that the
                 system spent in various states:

                 user   (1) Time spent in user mode.

                 nice   (2) Time spent in  user  mode  with  low  priority
                        (nice).

                 system (3) Time spent in system mode.

                 idle   (4)  Time  spent  in  the  idle  task.  This value
                        should be USER_HZ times the second  entry  in  the
                        /proc/uptime pseudo-file.

                 iowait (since Linux 2.5.41)
                        (5) Time waiting for I/O to complete.

                 irq (since Linux 2.6.0-test4)
                        (6) Time servicing interrupts.

                 softirq (since Linux 2.6.0-test4)
                        (7) Time servicing softirqs.

                 steal (since Linux 2.6.11)
                        (8)  Stolen time, which is the time spent in other
                        operating systems when running  in  a  virtualized
                        environment

                 guest (since Linux 2.6.24)
                        (9)  Time  spent  running  a virtual CPU for guest
                        operating systems under the control of  the  Linux
                        kernel.

                 guest_nice (since Linux 2.6.33)
                        (10) Time spent running a niced guest (virtual CPU
                        for guest operating systems under the  control  of
                        the Linux kernel).

          page 5741 1808
                 The  number  of  pages the system paged in and the number
                 that were paged out (from disk).

          swap 1 0
                 The number of swap pages that have been  brought  in  and
                 out.

          intr 1462898
                 This  line shows counts of interrupts serviced since boot
                 time, for each of the possible  system  interrupts.   The
                 first  column  is  the  total  of all interrupts serviced
                 including unnumbered  architecture  specific  interrupts;
                 each  subsequent  column is the total for that particular
                 numbered interrupt.  Unnumbered interrupts are not shown,
                 only summed into the total.

          disk_io: (2,0):(31,30,5764,1,2) (3,0):...
                 (major,disk_idx):(noinfo,     read_io_ops,     blks_read,
                 write_io_ops, blks_written)
                 (Linux 2.4 only)

          ctxt 115315
                 The number of context switches that the system underwent.

          btime 769041601
                 boot  time,  in  seconds  since  the  Epoch,   1970-01-01
                 00:00:00 +0000 (UTC).

          processes 86031
                 Number of forks since boot.

          procs_running 6
                 Number  of  processes  in  runnable state.  (Linux 2.5.45
                 onward.)

          procs_blocked 2
                 Number of processes blocked waiting for I/O to  complete.
                 (Linux 2.5.45 onward.)

   /proc/swaps
          Swap areas in use.  See also swapon(8).

   /proc/sys
          This directory (present since 1.3.57) contains a number of files
          and subdirectories corresponding  to  kernel  variables.   These
          variables  can  be  read  and sometimes modified using the /proc
          filesystem, and the (deprecated) sysctl(2) system call.

          String values may be terminated by either '\0' or '\n'.

          Integer and long values may be written either in decimal  or  in
          hexadecimal  notation  (e.g.  0x3FFF).   When  writing  multiple
          integer or long values, these may be separated  by  any  of  the
          following  whitespace  characters:  ' ',  '\t',  or '\n'.  Using
          other separators leads to the error EINVAL.

   /proc/sys/abi (since Linux 2.4.10)
          This  directory  may  contain  files  with  application   binary
          information.     See    the    Linux    kernel    source    file
          Documentation/sysctl/abi.txt for more information.

   /proc/sys/debug
          This directory may be empty.

   /proc/sys/dev
          This  directory  contains  device-specific  information   (e.g.,
          dev/cdrom/info).  On some systems, it may be empty.

   /proc/sys/fs
          This  directory contains the files and subdirectories for kernel
          variables related to filesystems.

   /proc/sys/fs/binfmt_misc
          Documentation for files in this directory can be  found  in  the
          Linux kernel sources in Documentation/binfmt_misc.txt.

   /proc/sys/fs/dentry-state (since Linux 2.2)
          This file contains information about the status of the directory
          cache (dcache).   The  file  contains  six  numbers,  nr_dentry,
          nr_unused,   age_limit   (age  in  seconds),  want_pages  (pages
          requested by system) and two dummy values.

          * nr_dentry  is  the  number  of  allocated   dentries   (dcache
            entries).  This field is unused in Linux 2.2.

          * nr_unused is the number of unused dentries.

          * age_limit is the age in seconds after which dcache entries can
            be reclaimed when memory is short.

          * want_pages   is   nonzero   when   the   kernel   has   called
            shrink_dcache_pages() and the dcache isn't pruned yet.

   /proc/sys/fs/dir-notify-enable
          This file can be used to disable or enable the dnotify interface
          described in fcntl(2) on a system-wide basis.  A value of  0  in
          this file disables the interface, and a value of 1 enables it.

   /proc/sys/fs/dquot-max
          This file shows the maximum number of cached disk quota entries.
          On some (2.4) systems, it is not present.  If the number of free
          cached  disk quota entries is very low and you have some awesome
          number of simultaneous system users, you might want to raise the
          limit.

   /proc/sys/fs/dquot-nr
          This  file  shows the number of allocated disk quota entries and
          the number of free disk quota entries.

   /proc/sys/fs/epoll (since Linux 2.6.28)
          This directory contains the file max_user_watches, which can  be
          used  to limit the amount of kernel memory consumed by the epoll
          interface.  For further details, see epoll(7).

   /proc/sys/fs/file-max
          This file defines a system-wide limit  on  the  number  of  open
          files   for   all   processes.   System  calls  that  fail  when
          encountering this limit fail with the error ENFILE.   (See  also
          setrlimit(2),  which  can  be  used by a process to set the per-
          process limit, RLIMIT_NOFILE, on the  number  of  files  it  may
          open.)   If  you  get  lots  of error messages in the kernel log
          about running out of file handles (look for "VFS: file-max limit
          <number> reached"), try increasing this value:

              echo 100000 > /proc/sys/fs/file-max

          Privileged  processes  (CAP_SYS_ADMIN) can override the file-max
          limit.

   /proc/sys/fs/file-nr
          This (read-only) file contains  three  numbers:  the  number  of
          allocated  file  handles  (i.e.,  the  number of files presently
          opened); the number of free file handles; and the maximum number
          of file handles (i.e., the same value as /proc/sys/fs/file-max).
          If the number of allocated file handles is close to the maximum,
          you  should  consider increasing the maximum.  Before Linux 2.6,
          the kernel allocated file handles  dynamically,  but  it  didn't
          free  them  again.  Instead the free file handles were kept in a
          list for reallocation; the "free file handles"  value  indicates
          the  size  of  that  list.   A large number of free file handles
          indicates that there was a past peak in the usage of  open  file
          handles.  Since Linux 2.6, the kernel does deallocate freed file
          handles, and the "free file handles" value is always zero.

   /proc/sys/fs/inode-max (only present until Linux 2.2)
          This file contains the maximum number of in-memory inodes.  This
          value  should  be  3-4  times larger than the value in file-max,
          since stdin, stdout and network sockets also need  an  inode  to
          handle  them.  When you regularly run out of inodes, you need to
          increase this value.

          Starting with Linux 2.4, there is no longer a  static  limit  on
          the number of inodes, and this file is removed.

   /proc/sys/fs/inode-nr
          This file contains the first two values from inode-state.

   /proc/sys/fs/inode-state
          This  file  contains  seven  numbers: nr_inodes, nr_free_inodes,
          preshrink, and four dummy values (always zero).

          nr_inodes is the number of  inodes  the  system  has  allocated.
          nr_free_inodes represents the number of free inodes.

          preshrink  is  nonzero  when  the  nr_inodes > inode-max and the
          system needs to prune the inode list instead of allocating more;
          since Linux 2.4, this field is a dummy value (always zero).

   /proc/sys/fs/inotify (since Linux 2.6.13)
          This     directory     contains     files     max_queued_events,
          max_user_instances, and max_user_watches, that can  be  used  to
          limit  the  amount  of  kernel  memory  consumed  by the inotify
          interface.  For further details, see inotify(7).

   /proc/sys/fs/lease-break-time
          This file specifies the grace period that the kernel grants to a
          process  holding  a  file  lease  (fcntl(2)) after it has sent a
          signal to that process notifying  it  that  another  process  is
          waiting  to  open the file.  If the lease holder does not remove
          or downgrade the lease within  this  grace  period,  the  kernel
          forcibly breaks the lease.

   /proc/sys/fs/leases-enable
          This  file  can  be  used  to  enable  or  disable  file  leases
          (fcntl(2)) on a system-wide basis.  If this  file  contains  the
          value 0, leases are disabled.  A nonzero value enables leases.

   /proc/sys/fs/mqueue (since Linux 2.6.6)
          This   directory   contains   files  msg_max,  msgsize_max,  and
          queues_max, controlling the  resources  used  by  POSIX  message
          queues.  See mq_overview(7) for details.

   /proc/sys/fs/nr_open (since Linux 2.6.25)
          This   file   imposes   ceiling   on  the  value  to  which  the
          RLIMIT_NOFILE resource limit can be raised  (see  getrlimit(2)).
          This  ceiling  is  enforced for both unprivileged and privileged
          process.  The default value in this file  is  1048576.   (Before
          Linux  2.6.25,  the  ceiling for RLIMIT_NOFILE was hard-coded to
          the same value.)

   /proc/sys/fs/overflowgid and /proc/sys/fs/overflowuid
          These files allow you to change the value of the fixed  UID  and
          GID.   The  default  is  65534.   Some  filesystems support only
          16-bit UIDs and GIDs, although in Linux UIDs  and  GIDs  are  32
          bits.   When  one  of  these  filesystems is mounted with writes
          enabled, any UID or GID that would exceed 65535 is translated to
          the overflow value before being written to disk.

   /proc/sys/fs/pipe-max-size (since Linux 2.6.35)
          See pipe(7).

   /proc/sys/fs/pipe-user-pages-hard (since Linux 4.5)
          See pipe(7).

   /proc/sys/fs/pipe-user-pages-soft (since Linux 4.5)
          See pipe(7).

   /proc/sys/fs/protected_hardlinks (since Linux 3.6)
          When  the value in this file is 0, no restrictions are placed on
          the creation  of  hard  links  (i.e.,  this  is  the  historical
          behavior before Linux 3.6).  When the value in this file is 1, a
          hard link can be created to a target file only  if  one  of  the
          following conditions is true:

          *  The calling process has the CAP_FOWNER capability in its user
             namespace and the file UID has a mapping in the namespace.

          *  The filesystem UID of the process creating the  link  matches
             the   owner  (UID)  of  the  target  file  (as  described  in
             credentials(7), a process's filesystem UID  is  normally  the
             same as its effective UID).

          *  All of the following conditions are true:

              *  the target is a regular file;

              *  the  target  file  does not have its set-user-ID mode bit
                 enabled;

              *  the target file does not have both its  set-group-ID  and
                 group-executable mode bits enabled; and

              *  the  caller  has  permission to read and write the target
                 file (either via the file's permissions mask  or  because
                 it has suitable capabilities).

          The  default  value  in  this file is 0.  Setting the value to 1
          prevents a longstanding class of security issues caused by hard-
          link-based  time-of-check, time-of-use races, most commonly seen
          in world-writable directories such as /tmp.  The  common  method
          of  exploiting  this  flaw is to cross privilege boundaries when
          following a given hard link (i.e., a root process follows a hard
          link created by another user).  Additionally, on systems without
          separated  partitions,  this  stops  unauthorized   users   from
          "pinning"  vulnerable set-user-ID and set-group-ID files against
          being upgraded by  the  administrator,  or  linking  to  special
          files.

   /proc/sys/fs/protected_symlinks (since Linux 3.6)
          When  the value in this file is 0, no restrictions are placed on
          following symbolic links (i.e., this is the historical  behavior
          before  Linux  3.6).  When the value in this file is 1, symbolic
          links are followed only in the following circumstances:

          *  the filesystem UID of the process following the link  matches
             the  owner  (UID)  of  the  symbolic  link  (as  described in
             credentials(7), a process's filesystem UID  is  normally  the
             same as its effective UID);

          *  the link is not in a sticky world-writable directory; or

          *  the  symbolic  link  and  its  parent directory have the same
             owner (UID)

          A system call that fails to follow a symbolic  link  because  of
          the above restrictions returns the error EACCES in errno.

          The  default  value  in  this file is 0.  Setting the value to 1
          avoids a longstanding class of security issues based on time-of-
          check, time-of-use races when accessing symbolic links.

   /proc/sys/fs/suid_dumpable (since Linux 2.6.13)
          The  value  in  this  file is assigned to a process's "dumpable"
          flag in the circumstances described in prctl(2).  In effect, the
          value  in  this  file  determines  whether  core  dump files are
          produced  for   set-user-ID   or   otherwise   protected/tainted
          binaries.   The "dumpable" setting also affects the ownership of
          files in a process's /proc/[pid] directory, as described above.

          Three different integer values can be specified:

          0 (default)
                 This  provides   the   traditional   (pre-Linux   2.6.13)
                 behavior.  A core dump will not be produced for a process
                 which has changed  credentials  (by  calling  seteuid(2),
                 setgid(2),  or  similar, or by executing a set-user-ID or
                 set-group-ID program) or whose binary does not have  read
                 permission enabled.

          1 ("debug")
                 All  processes  dump  core when possible.  (Reasons why a
                 process might nevertheless not dump core are described in
                 core(5).)   The core dump is owned by the filesystem user
                 ID of the dumping process and  no  security  is  applied.
                 This  is  intended  for system debugging situations only:
                 this mode is  insecure  because  it  allows  unprivileged
                 users  to  examine  the  memory  contents  of  privileged
                 processes.

          2 ("suidsafe")
                 Any binary which normally would not be  dumped  (see  "0"
                 above)  is dumped readable by root only.  This allows the
                 user to remove the core dump file but  not  to  read  it.
                 For  security  reasons  core  dumps in this mode will not
                 overwrite one another  or  other  files.   This  mode  is
                 appropriate  when  administrators are attempting to debug
                 problems in a normal environment.

                 Additionally,          since          Linux          3.6,
                 /proc/sys/kernel/core_pattern  must either be an absolute
                 pathname or a  pipe  command,  as  detailed  in  core(5).
                 Warnings   will   be   written   to  the  kernel  log  if
                 core_pattern does not follow these  rules,  and  no  core
                 dump will be produced.

          For  details  of the effect of a process's "dumpable" setting on
          ptrace access mode checking, see ptrace(2).

   /proc/sys/fs/super-max
          This file controls the maximum number of superblocks,  and  thus
          the  maximum  number of mounted filesystems the kernel can have.
          You need increase only super-max  if  you  need  to  mount  more
          filesystems than the current value in super-max allows you to.

   /proc/sys/fs/super-nr
          This file contains the number of filesystems currently mounted.

   /proc/sys/kernel
          This  directory  contains  files  controlling  a range of kernel
          parameters, as described below.

   /proc/sys/kernel/acct
          This file  contains  three  numbers:  highwater,  lowwater,  and
          frequency.   If  BSD-style  process accounting is enabled, these
          values control its behavior.  If free space on filesystem  where
          the  log lives goes below lowwater percent, accounting suspends.
          If free space gets above highwater percent, accounting  resumes.
          frequency  determines  how often the kernel checks the amount of
          free space (value is in seconds).  Default values are 4,  2  and
          30.   That  is,  suspend accounting if 2% or less space is free;
          resume it if 4% or more  space  is  free;  consider  information
          about amount of free space valid for 30 seconds.

   /proc/sys/kernel/auto_msgmni (Linux 2.6.27 to 3.18)
          From  Linux  2.6.27  to  3.18,  this  file  was  used to control
          recomputing of the value  in  /proc/sys/kernel/msgmni  upon  the
          addition   or   removal   of   memory   or  upon  IPC  namespace
          creation/removal.  Echoing "1" into  this  file  enabled  msgmni
          automatic  recomputing  (and triggered a recomputation of msgmni
          based on the current amount of available memory  and  number  of
          IPC  namespaces).   Echoing  "0" disabled automatic recomputing.
          (Automatic  recomputing  was  also  disabled  if  a  value   was
          explicitly  assigned  to  /proc/sys/kernel/msgmni.)  The default
          value in auto_msgmni was 1.

          Since Linux 3.19,  the  content  of  this  file  has  no  effect
          (because  msgmni  defaults  to near the maximum value possible),
          and reads from this file always return the value "0".

   /proc/sys/kernel/cap_last_cap (since Linux 3.2)
          See capabilities(7).

   /proc/sys/kernel/cap-bound (from Linux 2.2 to 2.6.24)
          This file holds the value of the kernel capability bounding  set
          (expressed  as  a  signed  decimal  number).   This set is ANDed
          against  the  capabilities  permitted  to   a   process   during
          execve(2).    Starting   with   Linux  2.6.25,  the  system-wide
          capability bounding set disappeared, and was replaced by a  per-
          thread bounding set; see capabilities(7).

   /proc/sys/kernel/core_pattern
          See core(5).

   /proc/sys/kernel/core_pipe_limit
          See core(5).

   /proc/sys/kernel/core_uses_pid
          See core(5).

   /proc/sys/kernel/ctrl-alt-del
          This  file  controls  the  handling  of  Ctrl-Alt-Del  from  the
          keyboard.  When the value in this file  is  0,  Ctrl-Alt-Del  is
          trapped  and  sent  to  the init(1) program to handle a graceful
          restart.  When the value is greater than zero, Linux's  reaction
          to  a  Vulcan  Nerve  Pinch  (tm)  will  be an immediate reboot,
          without even syncing its dirty buffers.  Note:  when  a  program
          (like  dosemu)  has the keyboard in "raw" mode, the ctrl-alt-del
          is intercepted by the program before it ever reaches the  kernel
          tty  layer, and it's up to the program to decide what to do with
          it.

   /proc/sys/kernel/dmesg_restrict (since Linux 2.6.37)
          The value in this file determines  who  can  see  kernel  syslog
          contents.   A  value  of 0 in this file imposes no restrictions.
          If the value is 1, only privileged users  can  read  the  kernel
          syslog.   (See  syslog(2)  for  more details.)  Since Linux 3.4,
          only users with the  CAP_SYS_ADMIN  capability  may  change  the
          value in this file.

   /proc/sys/kernel/domainname and /proc/sys/kernel/hostname
          can  be  used  to  set the NIS/YP domainname and the hostname of
          your box in exactly the same way as the  commands  domainname(1)
          and hostname(1), that is:

              # echo 'darkstar' > /proc/sys/kernel/hostname
              # echo 'mydomain' > /proc/sys/kernel/domainname

          has the same effect as

              # hostname 'darkstar'
              # domainname 'mydomain'

          Note,  however,  that  the  classic  darkstar.frop.org  has  the
          hostname  "darkstar"  and  DNS  (Internet  Domain  Name  Server)
          domainname  "frop.org", not to be confused with the NIS (Network
          Information Service) or YP (Yellow Pages) domainname.  These two
          domain   names   are  in  general  different.   For  a  detailed
          discussion see the hostname(1) man page.

   /proc/sys/kernel/hotplug
          This file contains the path for the hotplug policy  agent.   The
          default value in this file is /sbin/hotplug.

   /proc/sys/kernel/htab-reclaim
          (PowerPC  only)  If  this  file  is  set to a nonzero value, the
          PowerPC         htab          (see          kernel          file
          Documentation/powerpc/ppc_htab.txt)  is  pruned  each  time  the
          system hits the idle loop.

   /proc/sys/kernel/kptr_restrict (since Linux 2.6.38)
          The value in this file determines whether kernel  addresses  are
          exposed  via  /proc files and other interfaces.  A value of 0 in
          this file imposes no restrictions.  If the value  is  1,  kernel
          pointers printed using the %pK format specifier will be replaced
          with zeros unless the user has the  CAP_SYSLOG  capability.   If
          the  value  is  2,  kernel pointers printed using the %pK format
          specifier will be replaced with zeros regardless of  the  user's
          capabilities.   The  initial  default value for this file was 1,
          but the default was changed to 0 in Linux 2.6.39.   Since  Linux
          3.4, only users with the CAP_SYS_ADMIN capability can change the
          value in this file.

   /proc/sys/kernel/l2cr
          (PowerPC only) This file contains a flag that  controls  the  L2
          cache  of  G3  processor  boards.   If 0, the cache is disabled.
          Enabled if nonzero.

   /proc/sys/kernel/modprobe
          This file contains the path for the kernel module  loader.   The
          default  value  is  /sbin/modprobe.  The file is present only if
          the kernel is built  with  the  CONFIG_MODULES  (CONFIG_KMOD  in
          Linux  2.6.26  and  earlier) option enabled.  It is described by
          the Linux kernel  source  file  Documentation/kmod.txt  (present
          only in kernel 2.4 and earlier).

   /proc/sys/kernel/modules_disabled (since Linux 2.6.31)
          A toggle value indicating if modules are allowed to be loaded in
          an otherwise modular kernel.  This toggle defaults to  off  (0),
          but  can  be  set  true  (1).  Once true, modules can be neither
          loaded nor unloaded, and the toggle cannot be set back to false.
          The  file  is  present  only  if  the  kernel  is built with the
          CONFIG_MODULES option enabled.

   /proc/sys/kernel/msgmax (since Linux 2.2)
          This file defines a system-wide  limit  specifying  the  maximum
          number  of  bytes  in  a  single  message  written on a System V
          message queue.

   /proc/sys/kernel/msgmni (since Linux 2.4)
          This file defines the system-wide limit on the number of message
          queue identifiers.  See also /proc/sys/kernel/auto_msgmni.

   /proc/sys/kernel/msgmnb (since Linux 2.2)
          This file defines a system-wide parameter used to initialize the
          msg_qbytes setting for subsequently created message queues.  The
          msg_qbytes  setting  specifies  the maximum number of bytes that
          may be written to the message queue.

   /proc/sys/kernel/ngroups_max (since Linux 2.6.4)
          This is a read-only file that displays the upper  limit  on  the
          number of a process's group memberships.

   /proc/sys/kernel/ostype and /proc/sys/kernel/osrelease
          These files give substrings of /proc/version.

   /proc/sys/kernel/overflowgid and /proc/sys/kernel/overflowuid
          These  files  duplicate  the  files /proc/sys/fs/overflowgid and
          /proc/sys/fs/overflowuid.

   /proc/sys/kernel/panic
          This  file  gives  read/write  access  to  the  kernel  variable
          panic_timeout.   If  this  is  zero,  the  kernel will loop on a
          panic;  if  nonzero,  it  indicates  that  the   kernel   should
          autoreboot  after  this  number  of  seconds.   When you use the
          software watchdog device driver, the recommended setting is 60.

   /proc/sys/kernel/panic_on_oops (since Linux 2.5.68)
          This file controls the kernel's behavior when an oops or BUG  is
          encountered.   If this file contains 0, then the system tries to
          continue operation.  If it contains 1, then the system delays  a
          few  seconds  (to give klogd time to record the oops output) and
          then  panics.   If  the  /proc/sys/kernel/panic  file  is   also
          nonzero, then the machine will be rebooted.

   /proc/sys/kernel/pid_max (since Linux 2.5.34)
          This  file  specifies the value at which PIDs wrap around (i.e.,
          the value in this file is one greater  than  the  maximum  PID).
          PIDs  greater than this value are not allocated; thus, the value
          in this file also acts as  a  system-wide  limit  on  the  total
          number  of  processes  and  threads.  The default value for this
          file, 32768, results in the same range of  PIDs  as  on  earlier
          kernels.   On  32-bit  platforms, 32768 is the maximum value for
          pid_max.  On 64-bit systems, pid_max can be set to any value  up
          to 2^22 (PID_MAX_LIMIT, approximately 4 million).

   /proc/sys/kernel/powersave-nap (PowerPC only)
          This file contains a flag.  If set, Linux-PPC will use the "nap"
          mode of powersaving, otherwise the "doze" mode will be used.

   /proc/sys/kernel/printk
          See syslog(2).

   /proc/sys/kernel/pty (since Linux 2.6.4)
          This directory contains two files relating to the number of UNIX
          98 pseudoterminals (see pts(4)) on the system.

   /proc/sys/kernel/pty/max
          This file defines the maximum number of pseudoterminals.

   /proc/sys/kernel/pty/nr
          This  read-only  file  indicates  how  many  pseudoterminals are
          currently in use.

   /proc/sys/kernel/random
          This  directory  contains  various  parameters  controlling  the
          operation  of  the  file /dev/random.  See random(4) for further
          information.

   /proc/sys/kernel/random/uuid (since Linux 2.4)
          Each read from this read-only file returns a randomly  generated
          128-bit UUID, as a string in the standard UUID format.

   /proc/sys/kernel/randomize_va_space (since Linux 2.6.12)
          Select  the address space layout randomization (ASLR) policy for
          the system (on architectures that support ASLR).   Three  values
          are supported for this file:

          0  Turn  ASLR  off.   This is the default for architectures that
             don't support ASLR, and when the kernel is  booted  with  the
             norandmaps parameter.

          1  Make the addresses of mmap(2) allocations, the stack, and the
             VDSO page randomized.  Among other things,  this  means  that
             shared libraries will be loaded at randomized addresses.  The
             text segment of PIE-linked binaries will also be loaded at  a
             randomized  address.  This value is the default if the kernel
             was configured with CONFIG_COMPAT_BRK.

          2  (Since Linux 2.6.25) Also support heap  randomization.   This
             value  is  the  default if the kernel was not configured with
             CONFIG_COMPAT_BRK.

   /proc/sys/kernel/real-root-dev
          This  file  is  documented  in  the  Linux  kernel  source  file
          Documentation/initrd.txt.

   /proc/sys/kernel/reboot-cmd (Sparc only)
          This  file  seems  to  be a way to give an argument to the SPARC
          ROM/Flash boot loader.  Maybe  to  tell  it  what  to  do  after
          rebooting?

   /proc/sys/kernel/rtsig-max
          (Only  in  kernels  up to and including 2.6.7; see setrlimit(2))
          This file can be used to tune the maximum number of POSIX  real-
          time (queued) signals that can be outstanding in the system.

   /proc/sys/kernel/rtsig-nr
          (Only  in  kernels  up to and including 2.6.7.)  This file shows
          the number of POSIX real-time signals currently queued.

   /proc/[pid]/sched_autogroup_enabled (since Linux 2.6.38)
          See sched(7).

   /proc/sys/kernel/sched_rr_timeslice_ms (since Linux 3.9)
          See sched_rr_get_interval(2).

   /proc/sys/kernel/sched_rt_period_us (Since Linux 2.6.25)
          See sched(7).

   /proc/sys/kernel/sched_rt_runtime_us (Since Linux 2.6.25)
          See sched(7).

   /proc/sys/kernel/sem (since Linux 2.4)
          This file contains 4 numbers defining limits for  System  V  IPC
          semaphores.  These fields are, in order:

          SEMMSL  The maximum semaphores per semaphore set.

          SEMMNS  A  system-wide  limit on the number of semaphores in all
                  semaphore sets.

          SEMOPM  The maximum number of operations that may  be  specified
                  in a semop(2) call.

          SEMMNI  A  system-wide  limit on the maximum number of semaphore
                  identifiers.

   /proc/sys/kernel/sg-big-buff
          This file shows the size of the generic SCSI device (sg) buffer.
          You  can't  tune it just yet, but you could change it at compile
          time by editing include/scsi/sg.h  and  changing  the  value  of
          SG_BIG_BUFF.   However,  there shouldn't be any reason to change
          this value.

   /proc/sys/kernel/shm_rmid_forced (since Linux 3.1)
          If this file is set to 1, all System V  shared  memory  segments
          will be marked for destruction as soon as the number of attached
          processes falls to  zero;  in  other  words,  it  is  no  longer
          possible   to   create   shared   memory   segments  that  exist
          independently of any attached process.

          The effect is as though a shmctl(2) IPC_RMID is performed on all
          existing  segments as well as all segments created in the future
          (until this file is reset to 0).  Note  that  existing  segments
          that  are  attached  to no process will be immediately destroyed
          when this file is set to  1.   Setting  this  option  will  also
          destroy  segments  that  were  created, but never attached, upon
          termination  of  the  process  that  created  the  segment  with
          shmget(2).

          Setting  this  file  to  1  provides  a way of ensuring that all
          System V shared memory segments are counted against the resource
          usage  and  resource limits (see the description of RLIMIT_AS in
          getrlimit(2)) of at least one process.

          Because setting  this  file  to  1  produces  behavior  that  is
          nonstandard  and  could  also  break  existing applications, the
          default value in this file is 0.  Set this file to 1 only if you
          have  a  good understanding of the semantics of the applications
          using System V shared memory on your system.

   /proc/sys/kernel/shmall (since Linux 2.2)
          This file contains the system-wide limit on the total number  of
          pages of System V shared memory.

   /proc/sys/kernel/shmmax (since Linux 2.2)
          This file can be used to query and set the run-time limit on the
          maximum (System V IPC) shared memory segment size  that  can  be
          created.   Shared memory segments up to 1GB are now supported in
          the kernel.  This value defaults to SHMMAX.

   /proc/sys/kernel/shmmni (since Linux 2.4)
          This file specifies the system-wide maximum number of  System  V
          shared memory segments that can be created.

   /proc/sys/kernel/sysctl_writes_strict (since Linux 3.16)
          The  value  in  this file determines how the file offset affects
          the behavior of updating entries in files under /proc/sys.   The
          file has three possible values:

          -1  This  provides  legacy  handling,  with  no printk warnings.
              Each write(2) must fully contain the value  to  be  written,
              and  multiple  writes  on  the  same  file  descriptor  will
              overwrite the entire value, regardless of the file position.

          0   (default) This provides the same behavior  as  for  -1,  but
              printk  warnings  are  written  for  processes  that perform
              writes when the file offset is not 0.

          1   Respect the file offset when writing strings into  /proc/sys
              files.   Multiple  writes  will  append to the value buffer.
              Anything written beyond the  maximum  length  of  the  value
              buffer will be ignored.  Writes to numeric /proc/sys entries
              must always be at file offset 0 and the value must be  fully
              contained in the buffer provided to write(2).

   /proc/sys/kernel/sysrq
          This  file  controls  the functions allowed to be invoked by the
          SysRq key.  By default, the file contains 1 meaning  that  every
          possible  SysRq  request  is  allowed (in older kernel versions,
          SysRq  was  disabled  by  default,  and  you  were  required  to
          specifically enable it at run-time, but this is not the case any
          more).  Possible values in this file are:

          0    Disable sysrq completely

          1    Enable all functions of sysrq

          > 1  Bit mask of allowed sysrq functions, as follows:
                 2  Enable control of console logging level
                 4  Enable control of keyboard (SAK, unraw)
                 8  Enable debugging dumps of processes etc.
                16  Enable sync command
                32  Enable remount read-only
                64  Enable signaling of processes (term, kill, oom-kill)
               128  Allow reboot/poweroff
               256  Allow nicing of all real-time tasks

          This file is  present  only  if  the  CONFIG_MAGIC_SYSRQ  kernel
          configuration  option  is  enabled.  For further details see the
          Linux kernel source file Documentation/sysrq.txt.

   /proc/sys/kernel/version
          This file contains a string such as:

              #5 Wed Feb 25 21:49:24 MET 1998

          The "#5" means that this is the fifth  kernel  built  from  this
          source  base  and  the  date following it indicates the time the
          kernel was built.

   /proc/sys/kernel/threads-max (since Linux 2.3.11)
          This file specifies the  system-wide  limit  on  the  number  of
          threads (tasks) that can be created on the system.

          Since Linux 4.1, the value that can be written to threads-max is
          bounded.  The minimum value that can  be  written  is  20.   The
          maximum  value  that  can  be  written  is given by the constant
          FUTEX_TID_MASK (0x3fffffff).  If a value outside of  this  range
          is written to threads-max, the error EINVAL occurs.

          The  value  written  is checked against the available RAM pages.
          If the thread structures would occupy too much (more than 1/8th)
          of the available RAM pages, threads-max is reduced accordingly.

   /proc/sys/kernel/yama/ptrace_scope (since Linux 3.5)
          See ptrace(2).

   /proc/sys/kernel/zero-paged (PowerPC only)
          This  file  contains  a flag.  When enabled (nonzero), Linux-PPC
          will pre-zero pages in  the  idle  loop,  possibly  speeding  up
          get_free_pages.

   /proc/sys/net
          This directory contains networking stuff.  Explanations for some
          of the files under this directory can be  found  in  tcp(7)  and
          ip(7).

   /proc/sys/net/core/bpf_jit_enable
          See bpf(2).

   /proc/sys/net/core/somaxconn
          This  file  defines  a ceiling value for the backlog argument of
          listen(2); see the listen(2) manual page for details.

   /proc/sys/proc
          This directory may be empty.

   /proc/sys/sunrpc
          This directory supports Sun remote procedure  call  for  network
          filesystem (NFS).  On some systems, it is not present.

   /proc/sys/vm
          This  directory  contains  files  for  memory management tuning,
          buffer and cache management.

   /proc/sys/vm/compact_memory (since Linux 2.6.35)
          When 1 is written to this file, all  zones  are  compacted  such
          that  free  memory  is  available  in  contiguous  blocks  where
          possible.  The effect of this action can be  seen  by  examining
          /proc/buddyinfo.

          Present    only    if    the    kernel   was   configured   with
          CONFIG_COMPACTION.

   /proc/sys/vm/drop_caches (since Linux 2.6.16)
          Writing to this file causes the kernel  to  drop  clean  caches,
          dentries,  and inodes from memory, causing that memory to become
          free.  This can be useful  for  memory  management  testing  and
          performing  reproducible filesystem benchmarks.  Because writing
          to this file causes the benefits of caching to be lost,  it  can
          degrade overall system performance.

          To free pagecache, use:

              echo 1 > /proc/sys/vm/drop_caches

          To free dentries and inodes, use:

              echo 2 > /proc/sys/vm/drop_caches

          To free pagecache, dentries and inodes, use:

              echo 3 > /proc/sys/vm/drop_caches

          Because  writing  to this file is a nondestructive operation and
          dirty objects are not freeable,  the  user  should  run  sync(1)
          first.

   /proc/sys/vm/legacy_va_layout (since Linux 2.6.9)
          If  nonzero, this disables the new 32-bit memory-mapping layout;
          the kernel will use the legacy (2.4) layout for all processes.

   /proc/sys/vm/memory_failure_early_kill (since Linux 2.6.32)
          Control how to kill processes when an uncorrected  memory  error
          (typically  a  2-bit  error  in  a memory module) that cannot be
          handled by the kernel is detected in the background by hardware.
          In some cases (like the page still having a valid copy on disk),
          the  kernel  will  handle  the  failure  transparently   without
          affecting any applications.  But if there is no other up-to-date
          copy of the data, it will kill processes  to  prevent  any  data
          corruptions from propagating.

          The file has one of the following values:

          1:  Kill   all   processes   that  have  the  corrupted-and-not-
              reloadable  page  mapped  as  soon  as  the  corruption   is
              detected.   Note  that this is not supported for a few types
              of pages, such as kernel internally allocated  data  or  the
              swap cache, but works for the majority of user pages.

          0:  Unmap  the  corrupted  page  from  all  processes and kill a
              process only if it tries to access the page.

          The kill is performed using a SIGBUS signal with si_code set  to
          BUS_MCEERR_AO.   Processes  can handle this if they want to; see
          sigaction(2) for more details.

          This feature is  active  only  on  architectures/platforms  with
          advanced  machine  check  handling  and  depends on the hardware
          capabilities.

          Applications can override the memory_failure_early_kill  setting
          individually with the prctl(2) PR_MCE_KILL operation.

          Present    only    if    the    kernel   was   configured   with
          CONFIG_MEMORY_FAILURE.

   /proc/sys/vm/memory_failure_recovery (since Linux 2.6.32)
          Enable memory failure recovery (when supported by the platform)

          1:  Attempt recovery.

          0:  Always panic on a memory failure.

          Present   only   if   the    kernel    was    configured    with
          CONFIG_MEMORY_FAILURE.

   /proc/sys/vm/oom_dump_tasks (since Linux 2.6.25)
          Enables a system-wide task dump (excluding kernel threads) to be
          produced when the kernel  performs  an  OOM-killing.   The  dump
          includes  the  following  information  for  each  task  (thread,
          process): thread ID, real user ID, thread group ID (process ID),
          virtual memory size, resident set size, the CPU that the task is
          scheduled  on,   oom_adj   score   (see   the   description   of
          /proc/[pid]/oom_adj),  and  command  name.   This  is helpful to
          determine why the OOM-killer was invoked  and  to  identify  the
          rogue task that caused it.

          If this contains the value zero, this information is suppressed.
          On very large systems with thousands of tasks,  it  may  not  be
          feasible  to  dump  the  memory  state information for each one.
          Such systems should not be forced to incur a performance penalty
          in OOM situations when the information may not be desired.

          If  this  is  set to nonzero, this information is shown whenever
          the OOM-killer actually kills a memory-hogging task.

          The default value is 0.

   /proc/sys/vm/oom_kill_allocating_task (since Linux 2.6.24)
          This enables or disables killing the OOM-triggering task in out-
          of-memory situations.

          If  this  is  set  to zero, the OOM-killer will scan through the
          entire tasklist and select a task based on heuristics  to  kill.
          This  normally selects a rogue memory-hogging task that frees up
          a large amount of memory when killed.

          If this is set to nonzero, the OOM-killer simply kills the  task
          that  triggered  the  out-of-memory  condition.   This  avoids a
          possibly expensive tasklist scan.

          If /proc/sys/vm/panic_on_oom is  nonzero,  it  takes  precedence
          over        whatever        value        is        used       in
          /proc/sys/vm/oom_kill_allocating_task.

          The default value is 0.

   /proc/sys/vm/overcommit_kbytes (since Linux 3.14)
          This    writable    file    provides    an    alternative     to
          /proc/sys/vm/overcommit_ratio  for  controlling  the CommitLimit
          when /proc/sys/vm/overcommit_memory has the value 2.  It  allows
          the  amount  of  memory  overcommitting  to  be  specified as an
          absolute value (in kB), rather than as a percentage, as is  done
          with overcommit_ratio.  This allows for finer-grained control of
          CommitLimit on systems with extremely large memory sizes.

          Only one of overcommit_kbytes or overcommit_ratio  can  have  an
          effect:  if  overcommit_kbytes  has  a nonzero value, then it is
          used to calculate  CommitLimit,  otherwise  overcommit_ratio  is
          used.  Writing a value to either of these files causes the value
          in the other file to be set to zero.

   /proc/sys/vm/overcommit_memory
          This file contains the kernel virtual  memory  accounting  mode.
          Values are:

                 0: heuristic overcommit (this is the default)
                 1: always overcommit, never check
                 2: always check, never overcommit

          In  mode 0, calls of mmap(2) with MAP_NORESERVE are not checked,
          and the default check is very  weak,  leading  to  the  risk  of
          getting  a  process  "OOM-killed".  Under Linux 2.4, any nonzero
          value implies mode 1.

          In mode 2 (available since Linux 2.6), the total virtual address
          space  that  can  be allocated (CommitLimit in /proc/meminfo) is
          calculated as

              CommitLimit = (total_RAM - total_huge_TLB) *
                            overcommit_ratio / 100 + total_swap

          where:

               *  total_RAM is the total amount of RAM on the system;

               *  total_huge_TLB is the amount of  memory  set  aside  for
                  huge pages;

               *  overcommit_ratio       is       the       value       in
                  /proc/sys/vm/overcommit_ratio; and

               *  total_swap is the amount of swap space.

          For example, on a system with 16GB  of  physical  RAM,  16GB  of
          swap,  no space dedicated to huge pages, and an overcommit_ratio
          of 50, this formula yields a CommitLimit of 24GB.

          Since Linux 3.14, if the value in /proc/sys/vm/overcommit_kbytes
          is nonzero, then CommitLimit is instead calculated as:

              CommitLimit = overcommit_kbytes + total_swap

   /proc/sys/vm/overcommit_ratio (since Linux 2.6.0)
          This  writable  file defines a percentage by which memory can be
          overcommitted.  The default value in the file is  50.   See  the
          description of /proc/sys/vm/overcommit_memory.

   /proc/sys/vm/panic_on_oom (since Linux 2.6.18)
          This  enables  or  disables  a  kernel panic in an out-of-memory
          situation.

          If this file is set to the value 0, the kernel's OOM-killer will
          kill  some  rogue  process.   Usually, the OOM-killer is able to
          kill a rogue process and the system will survive.

          If this file is set to the value 1,  then  the  kernel  normally
          panics when out-of-memory happens.  However, if a process limits
          allocations to certain nodes  using  memory  policies  (mbind(2)
          MPOL_BIND)  or  cpusets (cpuset(7)) and those nodes reach memory
          exhaustion status, one process may be killed by the  OOM-killer.
          No panic occurs in this case: because other nodes' memory may be
          free, this means the system as a whole may not have  reached  an
          out-of-memory situation yet.

          If  this  file  is  set to the value 2, the kernel always panics
          when an out-of-memory condition occurs.

          The default value is 0.  1 and 2 are for failover of clustering.
          Select either according to your policy of failover.

   /proc/sys/vm/swappiness
          The value in this file controls how aggressively the kernel will
          swap memory pages.  Higher values increase aggressiveness, lower
          values decrease aggressiveness.  The default value is 60.

   /proc/sysrq-trigger (since Linux 2.4.21)
          Writing  a  character  to  this  file  triggers  the  same SysRq
          function as typing ALT-SysRq-<character> (see the description of
          /proc/sys/kernel/sysrq).  This file is normally writable only by
          root.  For further details see  the  Linux  kernel  source  file
          Documentation/sysrq.txt.

   /proc/sysvipc
          Subdirectory  containing  the  pseudo-files  msg,  sem  and shm.
          These files list the System V Interprocess  Communication  (IPC)
          objects  (respectively:  message  queues, semaphores, and shared
          memory) that currently exist on the  system,  providing  similar
          information  to  that  available  via ipcs(1).  These files have
          headers and are formatted (one IPC object  per  line)  for  easy
          understanding.   svipc(7)  provides  further  background  on the
          information shown by these files.

   /proc/thread-self (since Linux 3.17)
          This  directory  refers  to  the  thread  accessing  the   /proc
          filesystem,   and  is  identical  to  the  /proc/self/task/[tid]
          directory named by the process thread ID  ([tid])  of  the  same
          thread.

   /proc/timer_list (since Linux 2.6.21)
          This  read-only  file  exposes  a  list of all currently pending
          (high-resolution) timers, all  clock-event  sources,  and  their
          parameters in a human-readable form.

   /proc/timer_stats (since Linux 2.6.21)
          This  is  a  debugging facility to make timer (ab)use in a Linux
          system visible to kernel and user-space developers.  It  can  be
          used  by  kernel  and user-space developers to verify that their
          code does not make undue use of timers.  The goal  is  to  avoid
          unnecessary wakeups, thereby optimizing power consumption.

          If  enabled in the kernel (CONFIG_TIMER_STATS), but not used, it
          has almost zero runtime overhead and a  relatively  small  data-
          structure  overhead.   Even if collection is enabled at runtime,
          overhead is low: all  the  locking  is  per-CPU  and  lookup  is
          hashed.

          The  /proc/timer_stats  file  is  used  both to control sampling
          facility and to read out the sampled information.

          The timer_stats functionality is inactive on bootup.  A sampling
          period can be started using the following command:

              # echo 1 > /proc/timer_stats

          The following command stops a sampling period:

              # echo 0 > /proc/timer_stats

          The statistics can be retrieved by:

              $ cat /proc/timer_stats

          While  sampling  is enabled, each readout from /proc/timer_stats
          will see newly updated statistics.  Once sampling  is  disabled,
          the  sampled  information  is  kept until a new sample period is
          started.  This allows multiple readouts.

          Sample output from /proc/timer_stats:

   $ cat /proc/timer_stats
   Timer Stats Version: v0.3
   Sample period: 1.764 s
   Collection: active
     255,     0 swapper/3        hrtimer_start_range_ns (tick_sched_timer)
      71,     0 swapper/1        hrtimer_start_range_ns (tick_sched_timer)
      58,     0 swapper/0        hrtimer_start_range_ns (tick_sched_timer)
   4,  1694 gnome-shell      mod_delayed_work_on (delayed_work_timer_fn)
      17,     7 rcu_sched        rcu_gp_kthread (process_timeout)
   ...
   1,  4911 kworker/u16:0    mod_delayed_work_on (delayed_work_timer_fn)
      1D,  2522 kworker/0:0      queue_delayed_work_on (delayed_work_timer_fn)
   1029 total events, 583.333 events/sec

          The output columns are:

          *  a count of the number  of  events,  optionally  (since  Linux
             2.6.23)  followed  by  the letter 'D' if this is a deferrable
             timer;

          *  the PID of the process that initialized the timer;

          *  the name of the process that initialized the timer;

          *  the function where the timer was initialized; and

          *  (in parentheses) the callback  function  that  is  associated
             with the timer.

   /proc/tty
          Subdirectory  containing the pseudo-files and subdirectories for
          tty drivers and line disciplines.

   /proc/uptime
          This file  contains  two  numbers:  the  uptime  of  the  system
          (seconds),  and  the  amount  of  time  spent  in  idle  process
          (seconds).

   /proc/version
          This string identifies the  kernel  version  that  is  currently
          running.   It  includes the contents of /proc/sys/kernel/ostype,
          /proc/sys/kernel/osrelease  and  /proc/sys/kernel/version.   For
          example:
        Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994

   /proc/vmstat (since Linux 2.6.0)
          This file displays various virtual memory statistics.  Each line
          of this file contains a single  name-value  pair,  delimited  by
          white  space.   Some  files  are  present only if the kernel was
          configured with suitable options.  (In some cases,  the  options
          required   for  particular  files  have  changed  across  kernel
          versions, so they are not listed here.  Details can be found  by
          consulting the kernel source code.)  The following fields may be
          present:

          nr_free_pages (since Linux 2.6.31)

          nr_alloc_batch (since Linux 3.12)

          nr_inactive_anon (since Linux 2.6.28)

          nr_active_anon (since Linux 2.6.28)

          nr_inactive_file (since Linux 2.6.28)

          nr_active_file (since Linux 2.6.28)

          nr_unevictable (since Linux 2.6.28)

          nr_mlock (since Linux 2.6.28)

          nr_anon_pages (since Linux 2.6.18)

          nr_mapped (since Linux 2.6.0)

          nr_file_pages (since Linux 2.6.18)

          nr_dirty (since Linux 2.6.0)

          nr_writeback (since Linux 2.6.0)

          nr_slab_reclaimable (since Linux 2.6.19)

          nr_slab_unreclaimable (since Linux 2.6.19)

          nr_page_table_pages (since Linux 2.6.0)

          nr_kernel_stack (since Linux 2.6.32)
                 Amount of memory allocated to kernel stacks.

          nr_unstable (since Linux 2.6.0)

          nr_bounce (since Linux 2.6.12)

          nr_vmscan_write (since Linux 2.6.19)

          nr_vmscan_immediate_reclaim (since Linux 3.2)

          nr_writeback_temp (since Linux 2.6.26)

          nr_isolated_anon (since Linux 2.6.32)

          nr_isolated_file (since Linux 2.6.32)

          nr_shmem (since Linux 2.6.32)
                 Pages used by shmem and tmpfs(5).

          nr_dirtied (since Linux 2.6.37)

          nr_written (since Linux 2.6.37)

          nr_pages_scanned (since Linux 3.17)

          numa_hit (since Linux 2.6.18)

          numa_miss (since Linux 2.6.18)

          numa_foreign (since Linux 2.6.18)

          numa_interleave (since Linux 2.6.18)

          numa_local (since Linux 2.6.18)

          numa_other (since Linux 2.6.18)

          workingset_refault (since Linux 3.15)

          workingset_activate (since Linux 3.15)

          workingset_nodereclaim (since Linux 3.15)

          nr_anon_transparent_hugepages (since Linux 2.6.38)

          nr_free_cma (since Linux 3.7)
                 Number of free CMA (Contiguous Memory Allocator) pages.

          nr_dirty_threshold (since Linux 2.6.37)

          nr_dirty_background_threshold (since Linux 2.6.37)

          pgpgin (since Linux 2.6.0)

          pgpgout (since Linux 2.6.0)

          pswpin (since Linux 2.6.0)

          pswpout (since Linux 2.6.0)

          pgalloc_dma (since Linux 2.6.5)

          pgalloc_dma32 (since Linux 2.6.16)

          pgalloc_normal (since Linux 2.6.5)

          pgalloc_high (since Linux 2.6.5)

          pgalloc_movable (since Linux 2.6.23)

          pgfree (since Linux 2.6.0)

          pgactivate (since Linux 2.6.0)

          pgdeactivate (since Linux 2.6.0)

          pgfault (since Linux 2.6.0)

          pgmajfault (since Linux 2.6.0)

          pgrefill_dma (since Linux 2.6.5)

          pgrefill_dma32 (since Linux 2.6.16)

          pgrefill_normal (since Linux 2.6.5)

          pgrefill_high (since Linux 2.6.5)

          pgrefill_movable (since Linux 2.6.23)

          pgsteal_kswapd_dma (since Linux 3.4)

          pgsteal_kswapd_dma32 (since Linux 3.4)

          pgsteal_kswapd_normal (since Linux 3.4)

          pgsteal_kswapd_high (since Linux 3.4)

          pgsteal_kswapd_movable (since Linux 3.4)

          pgsteal_direct_dma

          pgsteal_direct_dma32 (since Linux 3.4)

          pgsteal_direct_normal (since Linux 3.4)

          pgsteal_direct_high (since Linux 3.4)

          pgsteal_direct_movable (since Linux 2.6.23)

          pgscan_kswapd_dma

          pgscan_kswapd_dma32 (since Linux 2.6.16)

          pgscan_kswapd_normal (since Linux 2.6.5)

          pgscan_kswapd_high

          pgscan_kswapd_movable (since Linux 2.6.23)

          pgscan_direct_dma

          pgscan_direct_dma32 (since Linux 2.6.16)

          pgscan_direct_normal

          pgscan_direct_high

          pgscan_direct_movable (since Linux 2.6.23)

          pgscan_direct_throttle (since Linux 3.6)

          zone_reclaim_failed (since linux 2.6.31)

          pginodesteal (since linux 2.6.0)

          slabs_scanned (since linux 2.6.5)

          kswapd_inodesteal (since linux 2.6.0)

          kswapd_low_wmark_hit_quickly (since 2.6.33)

          kswapd_high_wmark_hit_quickly (since 2.6.33)

          pageoutrun (since Linux 2.6.0)

          allocstall (since Linux 2.6.0)

          pgrotated (since Linux 2.6.0)

          drop_pagecache (since Linux 3.15)

          drop_slab (since Linux 3.15)

          numa_pte_updates (since Linux 3.8)

          numa_huge_pte_updates (since Linux 3.13)

          numa_hint_faults (since Linux 3.8)

          numa_hint_faults_local (since Linux 3.8)

          numa_pages_migrated (since Linux 3.8)

          pgmigrate_success (since Linux 3.8)

          pgmigrate_fail (since Linux 3.8)

          compact_migrate_scanned (since Linux 3.8)

          compact_free_scanned (since Linux 3.8)

          compact_isolated (since Linux 3.8)

          compact_stall (since Linux 2.6.35)
                 See        the         kernel         source         file
                 Documentation/vm/transhuge.txt.

          compact_fail (since Linux 2.6.35)
                 See         the         kernel         source        file
                 Documentation/vm/transhuge.txt.

          compact_success (since Linux 2.6.35)
                 See        the         kernel         source         file
                 Documentation/vm/transhuge.txt.

          htlb_buddy_alloc_success (since Linux 2.6.26)

          htlb_buddy_alloc_fail (since Linux 2.6.26)

          unevictable_pgs_culled (since Linux 2.6.28)

          unevictable_pgs_scanned (since Linux 2.6.28)

          unevictable_pgs_rescued (since Linux 2.6.28)

          unevictable_pgs_mlocked (since Linux 2.6.28)

          unevictable_pgs_munlocked (since Linux 2.6.28)

          unevictable_pgs_cleared (since Linux 2.6.28)

          unevictable_pgs_stranded (since Linux 2.6.28)

          thp_fault_alloc (since Linux 2.6.39)
                 See         the         kernel         source        file
                 Documentation/vm/transhuge.txt.

          thp_fault_fallback (since Linux 2.6.39)
                 See        the         kernel         source         file
                 Documentation/vm/transhuge.txt.

          thp_collapse_alloc (since Linux 2.6.39)
                 See         the         kernel         source        file
                 Documentation/vm/transhuge.txt.

          thp_collapse_alloc_failed (since Linux 2.6.39)
                 See        the         kernel         source         file
                 Documentation/vm/transhuge.txt.

          thp_split (since Linux 2.6.39)
                 See         the         kernel         source        file
                 Documentation/vm/transhuge.txt.

          thp_zero_page_alloc (since Linux 3.8)
                 See        the         kernel         source         file
                 Documentation/vm/transhuge.txt.

          thp_zero_page_alloc_failed (since Linux 3.8)
                 See         the         kernel         source        file
                 Documentation/vm/transhuge.txt.

          balloon_inflate (since Linux 3.18)

          balloon_deflate (since Linux 3.18)

          balloon_migrate (since Linux 3.18)

          nr_tlb_remote_flush (since Linux 3.12)

          nr_tlb_remote_flush_received (since Linux 3.12)

          nr_tlb_local_flush_all (since Linux 3.12)

          nr_tlb_local_flush_one (since Linux 3.12)

          vmacache_find_calls (since Linux 3.16)

          vmacache_find_hits (since Linux 3.16)

          vmacache_full_flushes (since Linux 3.19)

   /proc/zoneinfo (since Linux 2.6.13)
          This file display  information  about  memory  zones.   This  is
          useful for analyzing virtual memory behavior.

NOTES

   Many  strings  (i.e.,  the  environment  and  command  line) are in the
   internal format, with subfields terminated by null bytes ('\0'), so you
   may  find  that  things are more readable if you use od -c or tr "\000"
   "\n" to read them.  Alternatively, echo `cat <file>` works well.

   This manual page is incomplete, possibly inaccurate, and is the kind of
   thing that needs to be updated very often.

SEE ALSO

   cat(1),  dmesg(1),  find(1), free(1), init(1), ps(1), tr(1), uptime(1),
   chroot(2),  mmap(2),  readlink(2),  syslog(2),  slabinfo(5),   hier(7),
   namespaces(7),   time(7),  arp(8),  hdparm(8),  ifconfig(8),  lsmod(8),
   lspci(8), mount(8), netstat(8), procinfo(8), route(8), sysctl(8)

   The  Linux  kernel  source  files:   Documentation/filesystems/proc.txt
   Documentation/sysctl/fs.txt,           Documentation/sysctl/kernel.txt,
   Documentation/sysctl/net.txt, and Documentation/sysctl/vm.txt.

COLOPHON

   This page is part of release 4.09 of the Linux  man-pages  project.   A
   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at
   https://www.kernel.org/doc/man-pages/.





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